xref: /openbmc/linux/fs/9p/vfs_inode.c (revision 2c684d89)
1 /*
2  *  linux/fs/9p/vfs_inode.c
3  *
4  * This file contains vfs inode ops for the 9P2000 protocol.
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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
27 
28 #include <linux/module.h>
29 #include <linux/errno.h>
30 #include <linux/fs.h>
31 #include <linux/file.h>
32 #include <linux/pagemap.h>
33 #include <linux/stat.h>
34 #include <linux/string.h>
35 #include <linux/inet.h>
36 #include <linux/namei.h>
37 #include <linux/idr.h>
38 #include <linux/sched.h>
39 #include <linux/slab.h>
40 #include <linux/xattr.h>
41 #include <linux/posix_acl.h>
42 #include <net/9p/9p.h>
43 #include <net/9p/client.h>
44 
45 #include "v9fs.h"
46 #include "v9fs_vfs.h"
47 #include "fid.h"
48 #include "cache.h"
49 #include "xattr.h"
50 #include "acl.h"
51 
52 static const struct inode_operations v9fs_dir_inode_operations;
53 static const struct inode_operations v9fs_dir_inode_operations_dotu;
54 static const struct inode_operations v9fs_file_inode_operations;
55 static const struct inode_operations v9fs_symlink_inode_operations;
56 
57 /**
58  * unixmode2p9mode - convert unix mode bits to plan 9
59  * @v9ses: v9fs session information
60  * @mode: mode to convert
61  *
62  */
63 
64 static u32 unixmode2p9mode(struct v9fs_session_info *v9ses, umode_t mode)
65 {
66 	int res;
67 	res = mode & 0777;
68 	if (S_ISDIR(mode))
69 		res |= P9_DMDIR;
70 	if (v9fs_proto_dotu(v9ses)) {
71 		if (v9ses->nodev == 0) {
72 			if (S_ISSOCK(mode))
73 				res |= P9_DMSOCKET;
74 			if (S_ISFIFO(mode))
75 				res |= P9_DMNAMEDPIPE;
76 			if (S_ISBLK(mode))
77 				res |= P9_DMDEVICE;
78 			if (S_ISCHR(mode))
79 				res |= P9_DMDEVICE;
80 		}
81 
82 		if ((mode & S_ISUID) == S_ISUID)
83 			res |= P9_DMSETUID;
84 		if ((mode & S_ISGID) == S_ISGID)
85 			res |= P9_DMSETGID;
86 		if ((mode & S_ISVTX) == S_ISVTX)
87 			res |= P9_DMSETVTX;
88 	}
89 	return res;
90 }
91 
92 /**
93  * p9mode2perm- convert plan9 mode bits to unix permission bits
94  * @v9ses: v9fs session information
95  * @stat: p9_wstat from which mode need to be derived
96  *
97  */
98 static int p9mode2perm(struct v9fs_session_info *v9ses,
99 		       struct p9_wstat *stat)
100 {
101 	int res;
102 	int mode = stat->mode;
103 
104 	res = mode & S_IALLUGO;
105 	if (v9fs_proto_dotu(v9ses)) {
106 		if ((mode & P9_DMSETUID) == P9_DMSETUID)
107 			res |= S_ISUID;
108 
109 		if ((mode & P9_DMSETGID) == P9_DMSETGID)
110 			res |= S_ISGID;
111 
112 		if ((mode & P9_DMSETVTX) == P9_DMSETVTX)
113 			res |= S_ISVTX;
114 	}
115 	return res;
116 }
117 
118 /**
119  * p9mode2unixmode- convert plan9 mode bits to unix mode bits
120  * @v9ses: v9fs session information
121  * @stat: p9_wstat from which mode need to be derived
122  * @rdev: major number, minor number in case of device files.
123  *
124  */
125 static umode_t p9mode2unixmode(struct v9fs_session_info *v9ses,
126 			       struct p9_wstat *stat, dev_t *rdev)
127 {
128 	int res;
129 	u32 mode = stat->mode;
130 
131 	*rdev = 0;
132 	res = p9mode2perm(v9ses, stat);
133 
134 	if ((mode & P9_DMDIR) == P9_DMDIR)
135 		res |= S_IFDIR;
136 	else if ((mode & P9_DMSYMLINK) && (v9fs_proto_dotu(v9ses)))
137 		res |= S_IFLNK;
138 	else if ((mode & P9_DMSOCKET) && (v9fs_proto_dotu(v9ses))
139 		 && (v9ses->nodev == 0))
140 		res |= S_IFSOCK;
141 	else if ((mode & P9_DMNAMEDPIPE) && (v9fs_proto_dotu(v9ses))
142 		 && (v9ses->nodev == 0))
143 		res |= S_IFIFO;
144 	else if ((mode & P9_DMDEVICE) && (v9fs_proto_dotu(v9ses))
145 		 && (v9ses->nodev == 0)) {
146 		char type = 0, ext[32];
147 		int major = -1, minor = -1;
148 
149 		strlcpy(ext, stat->extension, sizeof(ext));
150 		sscanf(ext, "%c %i %i", &type, &major, &minor);
151 		switch (type) {
152 		case 'c':
153 			res |= S_IFCHR;
154 			break;
155 		case 'b':
156 			res |= S_IFBLK;
157 			break;
158 		default:
159 			p9_debug(P9_DEBUG_ERROR, "Unknown special type %c %s\n",
160 				 type, stat->extension);
161 		};
162 		*rdev = MKDEV(major, minor);
163 	} else
164 		res |= S_IFREG;
165 
166 	return res;
167 }
168 
169 /**
170  * v9fs_uflags2omode- convert posix open flags to plan 9 mode bits
171  * @uflags: flags to convert
172  * @extended: if .u extensions are active
173  */
174 
175 int v9fs_uflags2omode(int uflags, int extended)
176 {
177 	int ret;
178 
179 	ret = 0;
180 	switch (uflags&3) {
181 	default:
182 	case O_RDONLY:
183 		ret = P9_OREAD;
184 		break;
185 
186 	case O_WRONLY:
187 		ret = P9_OWRITE;
188 		break;
189 
190 	case O_RDWR:
191 		ret = P9_ORDWR;
192 		break;
193 	}
194 
195 	if (extended) {
196 		if (uflags & O_EXCL)
197 			ret |= P9_OEXCL;
198 
199 		if (uflags & O_APPEND)
200 			ret |= P9_OAPPEND;
201 	}
202 
203 	return ret;
204 }
205 
206 /**
207  * v9fs_blank_wstat - helper function to setup a 9P stat structure
208  * @wstat: structure to initialize
209  *
210  */
211 
212 void
213 v9fs_blank_wstat(struct p9_wstat *wstat)
214 {
215 	wstat->type = ~0;
216 	wstat->dev = ~0;
217 	wstat->qid.type = ~0;
218 	wstat->qid.version = ~0;
219 	*((long long *)&wstat->qid.path) = ~0;
220 	wstat->mode = ~0;
221 	wstat->atime = ~0;
222 	wstat->mtime = ~0;
223 	wstat->length = ~0;
224 	wstat->name = NULL;
225 	wstat->uid = NULL;
226 	wstat->gid = NULL;
227 	wstat->muid = NULL;
228 	wstat->n_uid = INVALID_UID;
229 	wstat->n_gid = INVALID_GID;
230 	wstat->n_muid = INVALID_UID;
231 	wstat->extension = NULL;
232 }
233 
234 /**
235  * v9fs_alloc_inode - helper function to allocate an inode
236  *
237  */
238 struct inode *v9fs_alloc_inode(struct super_block *sb)
239 {
240 	struct v9fs_inode *v9inode;
241 	v9inode = (struct v9fs_inode *)kmem_cache_alloc(v9fs_inode_cache,
242 							GFP_KERNEL);
243 	if (!v9inode)
244 		return NULL;
245 #ifdef CONFIG_9P_FSCACHE
246 	v9inode->fscache = NULL;
247 	spin_lock_init(&v9inode->fscache_lock);
248 #endif
249 	v9inode->writeback_fid = NULL;
250 	v9inode->cache_validity = 0;
251 	mutex_init(&v9inode->v_mutex);
252 	return &v9inode->vfs_inode;
253 }
254 
255 /**
256  * v9fs_destroy_inode - destroy an inode
257  *
258  */
259 
260 static void v9fs_i_callback(struct rcu_head *head)
261 {
262 	struct inode *inode = container_of(head, struct inode, i_rcu);
263 	kmem_cache_free(v9fs_inode_cache, V9FS_I(inode));
264 }
265 
266 void v9fs_destroy_inode(struct inode *inode)
267 {
268 	call_rcu(&inode->i_rcu, v9fs_i_callback);
269 }
270 
271 int v9fs_init_inode(struct v9fs_session_info *v9ses,
272 		    struct inode *inode, umode_t mode, dev_t rdev)
273 {
274 	int err = 0;
275 
276 	inode_init_owner(inode, NULL, mode);
277 	inode->i_blocks = 0;
278 	inode->i_rdev = rdev;
279 	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
280 	inode->i_mapping->a_ops = &v9fs_addr_operations;
281 
282 	switch (mode & S_IFMT) {
283 	case S_IFIFO:
284 	case S_IFBLK:
285 	case S_IFCHR:
286 	case S_IFSOCK:
287 		if (v9fs_proto_dotl(v9ses)) {
288 			inode->i_op = &v9fs_file_inode_operations_dotl;
289 		} else if (v9fs_proto_dotu(v9ses)) {
290 			inode->i_op = &v9fs_file_inode_operations;
291 		} else {
292 			p9_debug(P9_DEBUG_ERROR,
293 				 "special files without extended mode\n");
294 			err = -EINVAL;
295 			goto error;
296 		}
297 		init_special_inode(inode, inode->i_mode, inode->i_rdev);
298 		break;
299 	case S_IFREG:
300 		if (v9fs_proto_dotl(v9ses)) {
301 			inode->i_op = &v9fs_file_inode_operations_dotl;
302 			if (v9ses->cache == CACHE_LOOSE ||
303 			    v9ses->cache == CACHE_FSCACHE)
304 				inode->i_fop =
305 					&v9fs_cached_file_operations_dotl;
306 			else if (v9ses->cache == CACHE_MMAP)
307 				inode->i_fop = &v9fs_mmap_file_operations_dotl;
308 			else
309 				inode->i_fop = &v9fs_file_operations_dotl;
310 		} else {
311 			inode->i_op = &v9fs_file_inode_operations;
312 			if (v9ses->cache == CACHE_LOOSE ||
313 			    v9ses->cache == CACHE_FSCACHE)
314 				inode->i_fop =
315 					&v9fs_cached_file_operations;
316 			else if (v9ses->cache == CACHE_MMAP)
317 				inode->i_fop = &v9fs_mmap_file_operations;
318 			else
319 				inode->i_fop = &v9fs_file_operations;
320 		}
321 
322 		break;
323 	case S_IFLNK:
324 		if (!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)) {
325 			p9_debug(P9_DEBUG_ERROR,
326 				 "extended modes used with legacy protocol\n");
327 			err = -EINVAL;
328 			goto error;
329 		}
330 
331 		if (v9fs_proto_dotl(v9ses))
332 			inode->i_op = &v9fs_symlink_inode_operations_dotl;
333 		else
334 			inode->i_op = &v9fs_symlink_inode_operations;
335 
336 		break;
337 	case S_IFDIR:
338 		inc_nlink(inode);
339 		if (v9fs_proto_dotl(v9ses))
340 			inode->i_op = &v9fs_dir_inode_operations_dotl;
341 		else if (v9fs_proto_dotu(v9ses))
342 			inode->i_op = &v9fs_dir_inode_operations_dotu;
343 		else
344 			inode->i_op = &v9fs_dir_inode_operations;
345 
346 		if (v9fs_proto_dotl(v9ses))
347 			inode->i_fop = &v9fs_dir_operations_dotl;
348 		else
349 			inode->i_fop = &v9fs_dir_operations;
350 
351 		break;
352 	default:
353 		p9_debug(P9_DEBUG_ERROR, "BAD mode 0x%hx S_IFMT 0x%x\n",
354 			 mode, mode & S_IFMT);
355 		err = -EINVAL;
356 		goto error;
357 	}
358 error:
359 	return err;
360 
361 }
362 
363 /**
364  * v9fs_get_inode - helper function to setup an inode
365  * @sb: superblock
366  * @mode: mode to setup inode with
367  *
368  */
369 
370 struct inode *v9fs_get_inode(struct super_block *sb, umode_t mode, dev_t rdev)
371 {
372 	int err;
373 	struct inode *inode;
374 	struct v9fs_session_info *v9ses = sb->s_fs_info;
375 
376 	p9_debug(P9_DEBUG_VFS, "super block: %p mode: %ho\n", sb, mode);
377 
378 	inode = new_inode(sb);
379 	if (!inode) {
380 		pr_warn("%s (%d): Problem allocating inode\n",
381 			__func__, task_pid_nr(current));
382 		return ERR_PTR(-ENOMEM);
383 	}
384 	err = v9fs_init_inode(v9ses, inode, mode, rdev);
385 	if (err) {
386 		iput(inode);
387 		return ERR_PTR(err);
388 	}
389 	return inode;
390 }
391 
392 /*
393 static struct v9fs_fid*
394 v9fs_clone_walk(struct v9fs_session_info *v9ses, u32 fid, struct dentry *dentry)
395 {
396 	int err;
397 	int nfid;
398 	struct v9fs_fid *ret;
399 	struct v9fs_fcall *fcall;
400 
401 	nfid = v9fs_get_idpool(&v9ses->fidpool);
402 	if (nfid < 0) {
403 		eprintk(KERN_WARNING, "no free fids available\n");
404 		return ERR_PTR(-ENOSPC);
405 	}
406 
407 	err = v9fs_t_walk(v9ses, fid, nfid, (char *) dentry->d_name.name,
408 		&fcall);
409 
410 	if (err < 0) {
411 		if (fcall && fcall->id == RWALK)
412 			goto clunk_fid;
413 
414 		PRINT_FCALL_ERROR("walk error", fcall);
415 		v9fs_put_idpool(nfid, &v9ses->fidpool);
416 		goto error;
417 	}
418 
419 	kfree(fcall);
420 	fcall = NULL;
421 	ret = v9fs_fid_create(v9ses, nfid);
422 	if (!ret) {
423 		err = -ENOMEM;
424 		goto clunk_fid;
425 	}
426 
427 	err = v9fs_fid_insert(ret, dentry);
428 	if (err < 0) {
429 		v9fs_fid_destroy(ret);
430 		goto clunk_fid;
431 	}
432 
433 	return ret;
434 
435 clunk_fid:
436 	v9fs_t_clunk(v9ses, nfid);
437 
438 error:
439 	kfree(fcall);
440 	return ERR_PTR(err);
441 }
442 */
443 
444 
445 /**
446  * v9fs_clear_inode - release an inode
447  * @inode: inode to release
448  *
449  */
450 void v9fs_evict_inode(struct inode *inode)
451 {
452 	struct v9fs_inode *v9inode = V9FS_I(inode);
453 
454 	truncate_inode_pages_final(&inode->i_data);
455 	clear_inode(inode);
456 	filemap_fdatawrite(&inode->i_data);
457 
458 	v9fs_cache_inode_put_cookie(inode);
459 	/* clunk the fid stashed in writeback_fid */
460 	if (v9inode->writeback_fid) {
461 		p9_client_clunk(v9inode->writeback_fid);
462 		v9inode->writeback_fid = NULL;
463 	}
464 }
465 
466 static int v9fs_test_inode(struct inode *inode, void *data)
467 {
468 	int umode;
469 	dev_t rdev;
470 	struct v9fs_inode *v9inode = V9FS_I(inode);
471 	struct p9_wstat *st = (struct p9_wstat *)data;
472 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
473 
474 	umode = p9mode2unixmode(v9ses, st, &rdev);
475 	/* don't match inode of different type */
476 	if ((inode->i_mode & S_IFMT) != (umode & S_IFMT))
477 		return 0;
478 
479 	/* compare qid details */
480 	if (memcmp(&v9inode->qid.version,
481 		   &st->qid.version, sizeof(v9inode->qid.version)))
482 		return 0;
483 
484 	if (v9inode->qid.type != st->qid.type)
485 		return 0;
486 	return 1;
487 }
488 
489 static int v9fs_test_new_inode(struct inode *inode, void *data)
490 {
491 	return 0;
492 }
493 
494 static int v9fs_set_inode(struct inode *inode,  void *data)
495 {
496 	struct v9fs_inode *v9inode = V9FS_I(inode);
497 	struct p9_wstat *st = (struct p9_wstat *)data;
498 
499 	memcpy(&v9inode->qid, &st->qid, sizeof(st->qid));
500 	return 0;
501 }
502 
503 static struct inode *v9fs_qid_iget(struct super_block *sb,
504 				   struct p9_qid *qid,
505 				   struct p9_wstat *st,
506 				   int new)
507 {
508 	dev_t rdev;
509 	int retval;
510 	umode_t umode;
511 	unsigned long i_ino;
512 	struct inode *inode;
513 	struct v9fs_session_info *v9ses = sb->s_fs_info;
514 	int (*test)(struct inode *, void *);
515 
516 	if (new)
517 		test = v9fs_test_new_inode;
518 	else
519 		test = v9fs_test_inode;
520 
521 	i_ino = v9fs_qid2ino(qid);
522 	inode = iget5_locked(sb, i_ino, test, v9fs_set_inode, st);
523 	if (!inode)
524 		return ERR_PTR(-ENOMEM);
525 	if (!(inode->i_state & I_NEW))
526 		return inode;
527 	/*
528 	 * initialize the inode with the stat info
529 	 * FIXME!! we may need support for stale inodes
530 	 * later.
531 	 */
532 	inode->i_ino = i_ino;
533 	umode = p9mode2unixmode(v9ses, st, &rdev);
534 	retval = v9fs_init_inode(v9ses, inode, umode, rdev);
535 	if (retval)
536 		goto error;
537 
538 	v9fs_stat2inode(st, inode, sb);
539 	v9fs_cache_inode_get_cookie(inode);
540 	unlock_new_inode(inode);
541 	return inode;
542 error:
543 	iget_failed(inode);
544 	return ERR_PTR(retval);
545 
546 }
547 
548 struct inode *
549 v9fs_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
550 		    struct super_block *sb, int new)
551 {
552 	struct p9_wstat *st;
553 	struct inode *inode = NULL;
554 
555 	st = p9_client_stat(fid);
556 	if (IS_ERR(st))
557 		return ERR_CAST(st);
558 
559 	inode = v9fs_qid_iget(sb, &st->qid, st, new);
560 	p9stat_free(st);
561 	kfree(st);
562 	return inode;
563 }
564 
565 /**
566  * v9fs_at_to_dotl_flags- convert Linux specific AT flags to
567  * plan 9 AT flag.
568  * @flags: flags to convert
569  */
570 static int v9fs_at_to_dotl_flags(int flags)
571 {
572 	int rflags = 0;
573 	if (flags & AT_REMOVEDIR)
574 		rflags |= P9_DOTL_AT_REMOVEDIR;
575 	return rflags;
576 }
577 
578 /**
579  * v9fs_remove - helper function to remove files and directories
580  * @dir: directory inode that is being deleted
581  * @dentry:  dentry that is being deleted
582  * @flags: removing a directory
583  *
584  */
585 
586 static int v9fs_remove(struct inode *dir, struct dentry *dentry, int flags)
587 {
588 	struct inode *inode;
589 	int retval = -EOPNOTSUPP;
590 	struct p9_fid *v9fid, *dfid;
591 	struct v9fs_session_info *v9ses;
592 
593 	p9_debug(P9_DEBUG_VFS, "inode: %p dentry: %p rmdir: %x\n",
594 		 dir, dentry, flags);
595 
596 	v9ses = v9fs_inode2v9ses(dir);
597 	inode = d_inode(dentry);
598 	dfid = v9fs_fid_lookup(dentry->d_parent);
599 	if (IS_ERR(dfid)) {
600 		retval = PTR_ERR(dfid);
601 		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", retval);
602 		return retval;
603 	}
604 	if (v9fs_proto_dotl(v9ses))
605 		retval = p9_client_unlinkat(dfid, dentry->d_name.name,
606 					    v9fs_at_to_dotl_flags(flags));
607 	if (retval == -EOPNOTSUPP) {
608 		/* Try the one based on path */
609 		v9fid = v9fs_fid_clone(dentry);
610 		if (IS_ERR(v9fid))
611 			return PTR_ERR(v9fid);
612 		retval = p9_client_remove(v9fid);
613 	}
614 	if (!retval) {
615 		/*
616 		 * directories on unlink should have zero
617 		 * link count
618 		 */
619 		if (flags & AT_REMOVEDIR) {
620 			clear_nlink(inode);
621 			drop_nlink(dir);
622 		} else
623 			drop_nlink(inode);
624 
625 		v9fs_invalidate_inode_attr(inode);
626 		v9fs_invalidate_inode_attr(dir);
627 	}
628 	return retval;
629 }
630 
631 /**
632  * v9fs_create - Create a file
633  * @v9ses: session information
634  * @dir: directory that dentry is being created in
635  * @dentry:  dentry that is being created
636  * @extension: 9p2000.u extension string to support devices, etc.
637  * @perm: create permissions
638  * @mode: open mode
639  *
640  */
641 static struct p9_fid *
642 v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
643 		struct dentry *dentry, char *extension, u32 perm, u8 mode)
644 {
645 	int err;
646 	char *name;
647 	struct p9_fid *dfid, *ofid, *fid;
648 	struct inode *inode;
649 
650 	p9_debug(P9_DEBUG_VFS, "name %pd\n", dentry);
651 
652 	err = 0;
653 	ofid = NULL;
654 	fid = NULL;
655 	name = (char *) dentry->d_name.name;
656 	dfid = v9fs_fid_lookup(dentry->d_parent);
657 	if (IS_ERR(dfid)) {
658 		err = PTR_ERR(dfid);
659 		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", err);
660 		return ERR_PTR(err);
661 	}
662 
663 	/* clone a fid to use for creation */
664 	ofid = p9_client_walk(dfid, 0, NULL, 1);
665 	if (IS_ERR(ofid)) {
666 		err = PTR_ERR(ofid);
667 		p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n", err);
668 		return ERR_PTR(err);
669 	}
670 
671 	err = p9_client_fcreate(ofid, name, perm, mode, extension);
672 	if (err < 0) {
673 		p9_debug(P9_DEBUG_VFS, "p9_client_fcreate failed %d\n", err);
674 		goto error;
675 	}
676 
677 	if (!(perm & P9_DMLINK)) {
678 		/* now walk from the parent so we can get unopened fid */
679 		fid = p9_client_walk(dfid, 1, &name, 1);
680 		if (IS_ERR(fid)) {
681 			err = PTR_ERR(fid);
682 			p9_debug(P9_DEBUG_VFS,
683 				   "p9_client_walk failed %d\n", err);
684 			fid = NULL;
685 			goto error;
686 		}
687 		/*
688 		 * instantiate inode and assign the unopened fid to the dentry
689 		 */
690 		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
691 		if (IS_ERR(inode)) {
692 			err = PTR_ERR(inode);
693 			p9_debug(P9_DEBUG_VFS,
694 				   "inode creation failed %d\n", err);
695 			goto error;
696 		}
697 		v9fs_fid_add(dentry, fid);
698 		d_instantiate(dentry, inode);
699 	}
700 	return ofid;
701 error:
702 	if (ofid)
703 		p9_client_clunk(ofid);
704 
705 	if (fid)
706 		p9_client_clunk(fid);
707 
708 	return ERR_PTR(err);
709 }
710 
711 /**
712  * v9fs_vfs_create - VFS hook to create a regular file
713  *
714  * open(.., O_CREAT) is handled in v9fs_vfs_atomic_open().  This is only called
715  * for mknod(2).
716  *
717  * @dir: directory inode that is being created
718  * @dentry:  dentry that is being deleted
719  * @mode: create permissions
720  *
721  */
722 
723 static int
724 v9fs_vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
725 		bool excl)
726 {
727 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
728 	u32 perm = unixmode2p9mode(v9ses, mode);
729 	struct p9_fid *fid;
730 
731 	/* P9_OEXCL? */
732 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_ORDWR);
733 	if (IS_ERR(fid))
734 		return PTR_ERR(fid);
735 
736 	v9fs_invalidate_inode_attr(dir);
737 	p9_client_clunk(fid);
738 
739 	return 0;
740 }
741 
742 /**
743  * v9fs_vfs_mkdir - VFS mkdir hook to create a directory
744  * @dir:  inode that is being unlinked
745  * @dentry: dentry that is being unlinked
746  * @mode: mode for new directory
747  *
748  */
749 
750 static int v9fs_vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
751 {
752 	int err;
753 	u32 perm;
754 	struct p9_fid *fid;
755 	struct v9fs_session_info *v9ses;
756 
757 	p9_debug(P9_DEBUG_VFS, "name %pd\n", dentry);
758 	err = 0;
759 	v9ses = v9fs_inode2v9ses(dir);
760 	perm = unixmode2p9mode(v9ses, mode | S_IFDIR);
761 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_OREAD);
762 	if (IS_ERR(fid)) {
763 		err = PTR_ERR(fid);
764 		fid = NULL;
765 	} else {
766 		inc_nlink(dir);
767 		v9fs_invalidate_inode_attr(dir);
768 	}
769 
770 	if (fid)
771 		p9_client_clunk(fid);
772 
773 	return err;
774 }
775 
776 /**
777  * v9fs_vfs_lookup - VFS lookup hook to "walk" to a new inode
778  * @dir:  inode that is being walked from
779  * @dentry: dentry that is being walked to?
780  * @flags: lookup flags (unused)
781  *
782  */
783 
784 struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
785 				      unsigned int flags)
786 {
787 	struct dentry *res;
788 	struct v9fs_session_info *v9ses;
789 	struct p9_fid *dfid, *fid;
790 	struct inode *inode;
791 	char *name;
792 
793 	p9_debug(P9_DEBUG_VFS, "dir: %p dentry: (%pd) %p flags: %x\n",
794 		 dir, dentry, dentry, flags);
795 
796 	if (dentry->d_name.len > NAME_MAX)
797 		return ERR_PTR(-ENAMETOOLONG);
798 
799 	v9ses = v9fs_inode2v9ses(dir);
800 	/* We can walk d_parent because we hold the dir->i_mutex */
801 	dfid = v9fs_fid_lookup(dentry->d_parent);
802 	if (IS_ERR(dfid))
803 		return ERR_CAST(dfid);
804 
805 	name = (char *) dentry->d_name.name;
806 	fid = p9_client_walk(dfid, 1, &name, 1);
807 	if (IS_ERR(fid)) {
808 		if (fid == ERR_PTR(-ENOENT)) {
809 			d_add(dentry, NULL);
810 			return NULL;
811 		}
812 		return ERR_CAST(fid);
813 	}
814 	/*
815 	 * Make sure we don't use a wrong inode due to parallel
816 	 * unlink. For cached mode create calls request for new
817 	 * inode. But with cache disabled, lookup should do this.
818 	 */
819 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
820 		inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
821 	else
822 		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
823 	if (IS_ERR(inode)) {
824 		p9_client_clunk(fid);
825 		return ERR_CAST(inode);
826 	}
827 	/*
828 	 * If we had a rename on the server and a parallel lookup
829 	 * for the new name, then make sure we instantiate with
830 	 * the new name. ie look up for a/b, while on server somebody
831 	 * moved b under k and client parallely did a lookup for
832 	 * k/b.
833 	 */
834 	res = d_splice_alias(inode, dentry);
835 	if (!res)
836 		v9fs_fid_add(dentry, fid);
837 	else if (!IS_ERR(res))
838 		v9fs_fid_add(res, fid);
839 	else
840 		p9_client_clunk(fid);
841 	return res;
842 }
843 
844 static int
845 v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
846 		     struct file *file, unsigned flags, umode_t mode,
847 		     int *opened)
848 {
849 	int err;
850 	u32 perm;
851 	struct v9fs_inode *v9inode;
852 	struct v9fs_session_info *v9ses;
853 	struct p9_fid *fid, *inode_fid;
854 	struct dentry *res = NULL;
855 
856 	if (d_unhashed(dentry)) {
857 		res = v9fs_vfs_lookup(dir, dentry, 0);
858 		if (IS_ERR(res))
859 			return PTR_ERR(res);
860 
861 		if (res)
862 			dentry = res;
863 	}
864 
865 	/* Only creates */
866 	if (!(flags & O_CREAT) || d_really_is_positive(dentry))
867 		return finish_no_open(file, res);
868 
869 	err = 0;
870 
871 	v9ses = v9fs_inode2v9ses(dir);
872 	perm = unixmode2p9mode(v9ses, mode);
873 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm,
874 				v9fs_uflags2omode(flags,
875 						v9fs_proto_dotu(v9ses)));
876 	if (IS_ERR(fid)) {
877 		err = PTR_ERR(fid);
878 		fid = NULL;
879 		goto error;
880 	}
881 
882 	v9fs_invalidate_inode_attr(dir);
883 	v9inode = V9FS_I(d_inode(dentry));
884 	mutex_lock(&v9inode->v_mutex);
885 	if ((v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) &&
886 	    !v9inode->writeback_fid &&
887 	    ((flags & O_ACCMODE) != O_RDONLY)) {
888 		/*
889 		 * clone a fid and add it to writeback_fid
890 		 * we do it during open time instead of
891 		 * page dirty time via write_begin/page_mkwrite
892 		 * because we want write after unlink usecase
893 		 * to work.
894 		 */
895 		inode_fid = v9fs_writeback_fid(dentry);
896 		if (IS_ERR(inode_fid)) {
897 			err = PTR_ERR(inode_fid);
898 			mutex_unlock(&v9inode->v_mutex);
899 			goto error;
900 		}
901 		v9inode->writeback_fid = (void *) inode_fid;
902 	}
903 	mutex_unlock(&v9inode->v_mutex);
904 	err = finish_open(file, dentry, generic_file_open, opened);
905 	if (err)
906 		goto error;
907 
908 	file->private_data = fid;
909 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
910 		v9fs_cache_inode_set_cookie(d_inode(dentry), file);
911 
912 	*opened |= FILE_CREATED;
913 out:
914 	dput(res);
915 	return err;
916 
917 error:
918 	if (fid)
919 		p9_client_clunk(fid);
920 	goto out;
921 }
922 
923 /**
924  * v9fs_vfs_unlink - VFS unlink hook to delete an inode
925  * @i:  inode that is being unlinked
926  * @d: dentry that is being unlinked
927  *
928  */
929 
930 int v9fs_vfs_unlink(struct inode *i, struct dentry *d)
931 {
932 	return v9fs_remove(i, d, 0);
933 }
934 
935 /**
936  * v9fs_vfs_rmdir - VFS unlink hook to delete a directory
937  * @i:  inode that is being unlinked
938  * @d: dentry that is being unlinked
939  *
940  */
941 
942 int v9fs_vfs_rmdir(struct inode *i, struct dentry *d)
943 {
944 	return v9fs_remove(i, d, AT_REMOVEDIR);
945 }
946 
947 /**
948  * v9fs_vfs_rename - VFS hook to rename an inode
949  * @old_dir:  old dir inode
950  * @old_dentry: old dentry
951  * @new_dir: new dir inode
952  * @new_dentry: new dentry
953  *
954  */
955 
956 int
957 v9fs_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
958 		struct inode *new_dir, struct dentry *new_dentry)
959 {
960 	int retval;
961 	struct inode *old_inode;
962 	struct inode *new_inode;
963 	struct v9fs_session_info *v9ses;
964 	struct p9_fid *oldfid;
965 	struct p9_fid *olddirfid;
966 	struct p9_fid *newdirfid;
967 	struct p9_wstat wstat;
968 
969 	p9_debug(P9_DEBUG_VFS, "\n");
970 	retval = 0;
971 	old_inode = d_inode(old_dentry);
972 	new_inode = d_inode(new_dentry);
973 	v9ses = v9fs_inode2v9ses(old_inode);
974 	oldfid = v9fs_fid_lookup(old_dentry);
975 	if (IS_ERR(oldfid))
976 		return PTR_ERR(oldfid);
977 
978 	olddirfid = v9fs_fid_clone(old_dentry->d_parent);
979 	if (IS_ERR(olddirfid)) {
980 		retval = PTR_ERR(olddirfid);
981 		goto done;
982 	}
983 
984 	newdirfid = v9fs_fid_clone(new_dentry->d_parent);
985 	if (IS_ERR(newdirfid)) {
986 		retval = PTR_ERR(newdirfid);
987 		goto clunk_olddir;
988 	}
989 
990 	down_write(&v9ses->rename_sem);
991 	if (v9fs_proto_dotl(v9ses)) {
992 		retval = p9_client_renameat(olddirfid, old_dentry->d_name.name,
993 					    newdirfid, new_dentry->d_name.name);
994 		if (retval == -EOPNOTSUPP)
995 			retval = p9_client_rename(oldfid, newdirfid,
996 						  new_dentry->d_name.name);
997 		if (retval != -EOPNOTSUPP)
998 			goto clunk_newdir;
999 	}
1000 	if (old_dentry->d_parent != new_dentry->d_parent) {
1001 		/*
1002 		 * 9P .u can only handle file rename in the same directory
1003 		 */
1004 
1005 		p9_debug(P9_DEBUG_ERROR, "old dir and new dir are different\n");
1006 		retval = -EXDEV;
1007 		goto clunk_newdir;
1008 	}
1009 	v9fs_blank_wstat(&wstat);
1010 	wstat.muid = v9ses->uname;
1011 	wstat.name = (char *) new_dentry->d_name.name;
1012 	retval = p9_client_wstat(oldfid, &wstat);
1013 
1014 clunk_newdir:
1015 	if (!retval) {
1016 		if (new_inode) {
1017 			if (S_ISDIR(new_inode->i_mode))
1018 				clear_nlink(new_inode);
1019 			else
1020 				drop_nlink(new_inode);
1021 		}
1022 		if (S_ISDIR(old_inode->i_mode)) {
1023 			if (!new_inode)
1024 				inc_nlink(new_dir);
1025 			drop_nlink(old_dir);
1026 		}
1027 		v9fs_invalidate_inode_attr(old_inode);
1028 		v9fs_invalidate_inode_attr(old_dir);
1029 		v9fs_invalidate_inode_attr(new_dir);
1030 
1031 		/* successful rename */
1032 		d_move(old_dentry, new_dentry);
1033 	}
1034 	up_write(&v9ses->rename_sem);
1035 	p9_client_clunk(newdirfid);
1036 
1037 clunk_olddir:
1038 	p9_client_clunk(olddirfid);
1039 
1040 done:
1041 	return retval;
1042 }
1043 
1044 /**
1045  * v9fs_vfs_getattr - retrieve file metadata
1046  * @mnt: mount information
1047  * @dentry: file to get attributes on
1048  * @stat: metadata structure to populate
1049  *
1050  */
1051 
1052 static int
1053 v9fs_vfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
1054 		 struct kstat *stat)
1055 {
1056 	struct v9fs_session_info *v9ses;
1057 	struct p9_fid *fid;
1058 	struct p9_wstat *st;
1059 
1060 	p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
1061 	v9ses = v9fs_dentry2v9ses(dentry);
1062 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
1063 		generic_fillattr(d_inode(dentry), stat);
1064 		return 0;
1065 	}
1066 	fid = v9fs_fid_lookup(dentry);
1067 	if (IS_ERR(fid))
1068 		return PTR_ERR(fid);
1069 
1070 	st = p9_client_stat(fid);
1071 	if (IS_ERR(st))
1072 		return PTR_ERR(st);
1073 
1074 	v9fs_stat2inode(st, d_inode(dentry), d_inode(dentry)->i_sb);
1075 	generic_fillattr(d_inode(dentry), stat);
1076 
1077 	p9stat_free(st);
1078 	kfree(st);
1079 	return 0;
1080 }
1081 
1082 /**
1083  * v9fs_vfs_setattr - set file metadata
1084  * @dentry: file whose metadata to set
1085  * @iattr: metadata assignment structure
1086  *
1087  */
1088 
1089 static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
1090 {
1091 	int retval;
1092 	struct v9fs_session_info *v9ses;
1093 	struct p9_fid *fid;
1094 	struct p9_wstat wstat;
1095 
1096 	p9_debug(P9_DEBUG_VFS, "\n");
1097 	retval = inode_change_ok(d_inode(dentry), iattr);
1098 	if (retval)
1099 		return retval;
1100 
1101 	retval = -EPERM;
1102 	v9ses = v9fs_dentry2v9ses(dentry);
1103 	fid = v9fs_fid_lookup(dentry);
1104 	if(IS_ERR(fid))
1105 		return PTR_ERR(fid);
1106 
1107 	v9fs_blank_wstat(&wstat);
1108 	if (iattr->ia_valid & ATTR_MODE)
1109 		wstat.mode = unixmode2p9mode(v9ses, iattr->ia_mode);
1110 
1111 	if (iattr->ia_valid & ATTR_MTIME)
1112 		wstat.mtime = iattr->ia_mtime.tv_sec;
1113 
1114 	if (iattr->ia_valid & ATTR_ATIME)
1115 		wstat.atime = iattr->ia_atime.tv_sec;
1116 
1117 	if (iattr->ia_valid & ATTR_SIZE)
1118 		wstat.length = iattr->ia_size;
1119 
1120 	if (v9fs_proto_dotu(v9ses)) {
1121 		if (iattr->ia_valid & ATTR_UID)
1122 			wstat.n_uid = iattr->ia_uid;
1123 
1124 		if (iattr->ia_valid & ATTR_GID)
1125 			wstat.n_gid = iattr->ia_gid;
1126 	}
1127 
1128 	/* Write all dirty data */
1129 	if (d_is_reg(dentry))
1130 		filemap_write_and_wait(d_inode(dentry)->i_mapping);
1131 
1132 	retval = p9_client_wstat(fid, &wstat);
1133 	if (retval < 0)
1134 		return retval;
1135 
1136 	if ((iattr->ia_valid & ATTR_SIZE) &&
1137 	    iattr->ia_size != i_size_read(d_inode(dentry)))
1138 		truncate_setsize(d_inode(dentry), iattr->ia_size);
1139 
1140 	v9fs_invalidate_inode_attr(d_inode(dentry));
1141 
1142 	setattr_copy(d_inode(dentry), iattr);
1143 	mark_inode_dirty(d_inode(dentry));
1144 	return 0;
1145 }
1146 
1147 /**
1148  * v9fs_stat2inode - populate an inode structure with mistat info
1149  * @stat: Plan 9 metadata (mistat) structure
1150  * @inode: inode to populate
1151  * @sb: superblock of filesystem
1152  *
1153  */
1154 
1155 void
1156 v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
1157 	struct super_block *sb)
1158 {
1159 	umode_t mode;
1160 	char ext[32];
1161 	char tag_name[14];
1162 	unsigned int i_nlink;
1163 	struct v9fs_session_info *v9ses = sb->s_fs_info;
1164 	struct v9fs_inode *v9inode = V9FS_I(inode);
1165 
1166 	set_nlink(inode, 1);
1167 
1168 	inode->i_atime.tv_sec = stat->atime;
1169 	inode->i_mtime.tv_sec = stat->mtime;
1170 	inode->i_ctime.tv_sec = stat->mtime;
1171 
1172 	inode->i_uid = v9ses->dfltuid;
1173 	inode->i_gid = v9ses->dfltgid;
1174 
1175 	if (v9fs_proto_dotu(v9ses)) {
1176 		inode->i_uid = stat->n_uid;
1177 		inode->i_gid = stat->n_gid;
1178 	}
1179 	if ((S_ISREG(inode->i_mode)) || (S_ISDIR(inode->i_mode))) {
1180 		if (v9fs_proto_dotu(v9ses) && (stat->extension[0] != '\0')) {
1181 			/*
1182 			 * Hadlink support got added later to
1183 			 * to the .u extension. So there can be
1184 			 * server out there that doesn't support
1185 			 * this even with .u extension. So check
1186 			 * for non NULL stat->extension
1187 			 */
1188 			strlcpy(ext, stat->extension, sizeof(ext));
1189 			/* HARDLINKCOUNT %u */
1190 			sscanf(ext, "%13s %u", tag_name, &i_nlink);
1191 			if (!strncmp(tag_name, "HARDLINKCOUNT", 13))
1192 				set_nlink(inode, i_nlink);
1193 		}
1194 	}
1195 	mode = p9mode2perm(v9ses, stat);
1196 	mode |= inode->i_mode & ~S_IALLUGO;
1197 	inode->i_mode = mode;
1198 	i_size_write(inode, stat->length);
1199 
1200 	/* not real number of blocks, but 512 byte ones ... */
1201 	inode->i_blocks = (i_size_read(inode) + 512 - 1) >> 9;
1202 	v9inode->cache_validity &= ~V9FS_INO_INVALID_ATTR;
1203 }
1204 
1205 /**
1206  * v9fs_qid2ino - convert qid into inode number
1207  * @qid: qid to hash
1208  *
1209  * BUG: potential for inode number collisions?
1210  */
1211 
1212 ino_t v9fs_qid2ino(struct p9_qid *qid)
1213 {
1214 	u64 path = qid->path + 2;
1215 	ino_t i = 0;
1216 
1217 	if (sizeof(ino_t) == sizeof(path))
1218 		memcpy(&i, &path, sizeof(ino_t));
1219 	else
1220 		i = (ino_t) (path ^ (path >> 32));
1221 
1222 	return i;
1223 }
1224 
1225 /**
1226  * v9fs_vfs_follow_link - follow a symlink path
1227  * @dentry: dentry for symlink
1228  * @cookie: place to pass the data to put_link()
1229  */
1230 
1231 static const char *v9fs_vfs_follow_link(struct dentry *dentry, void **cookie)
1232 {
1233 	struct v9fs_session_info *v9ses = v9fs_dentry2v9ses(dentry);
1234 	struct p9_fid *fid = v9fs_fid_lookup(dentry);
1235 	struct p9_wstat *st;
1236 	char *res;
1237 
1238 	p9_debug(P9_DEBUG_VFS, "%pd\n", dentry);
1239 
1240 	if (IS_ERR(fid))
1241 		return ERR_CAST(fid);
1242 
1243 	if (!v9fs_proto_dotu(v9ses))
1244 		return ERR_PTR(-EBADF);
1245 
1246 	st = p9_client_stat(fid);
1247 	if (IS_ERR(st))
1248 		return ERR_CAST(st);
1249 
1250 	if (!(st->mode & P9_DMSYMLINK)) {
1251 		p9stat_free(st);
1252 		kfree(st);
1253 		return ERR_PTR(-EINVAL);
1254 	}
1255 	res = st->extension;
1256 	st->extension = NULL;
1257 	if (strlen(res) >= PATH_MAX)
1258 		res[PATH_MAX - 1] = '\0';
1259 
1260 	p9stat_free(st);
1261 	kfree(st);
1262 	return *cookie = res;
1263 }
1264 
1265 /**
1266  * v9fs_vfs_mkspecial - create a special file
1267  * @dir: inode to create special file in
1268  * @dentry: dentry to create
1269  * @perm: mode to create special file
1270  * @extension: 9p2000.u format extension string representing special file
1271  *
1272  */
1273 
1274 static int v9fs_vfs_mkspecial(struct inode *dir, struct dentry *dentry,
1275 	u32 perm, const char *extension)
1276 {
1277 	struct p9_fid *fid;
1278 	struct v9fs_session_info *v9ses;
1279 
1280 	v9ses = v9fs_inode2v9ses(dir);
1281 	if (!v9fs_proto_dotu(v9ses)) {
1282 		p9_debug(P9_DEBUG_ERROR, "not extended\n");
1283 		return -EPERM;
1284 	}
1285 
1286 	fid = v9fs_create(v9ses, dir, dentry, (char *) extension, perm,
1287 								P9_OREAD);
1288 	if (IS_ERR(fid))
1289 		return PTR_ERR(fid);
1290 
1291 	v9fs_invalidate_inode_attr(dir);
1292 	p9_client_clunk(fid);
1293 	return 0;
1294 }
1295 
1296 /**
1297  * v9fs_vfs_symlink - helper function to create symlinks
1298  * @dir: directory inode containing symlink
1299  * @dentry: dentry for symlink
1300  * @symname: symlink data
1301  *
1302  * See Also: 9P2000.u RFC for more information
1303  *
1304  */
1305 
1306 static int
1307 v9fs_vfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1308 {
1309 	p9_debug(P9_DEBUG_VFS, " %lu,%pd,%s\n",
1310 		 dir->i_ino, dentry, symname);
1311 
1312 	return v9fs_vfs_mkspecial(dir, dentry, P9_DMSYMLINK, symname);
1313 }
1314 
1315 #define U32_MAX_DIGITS 10
1316 
1317 /**
1318  * v9fs_vfs_link - create a hardlink
1319  * @old_dentry: dentry for file to link to
1320  * @dir: inode destination for new link
1321  * @dentry: dentry for link
1322  *
1323  */
1324 
1325 static int
1326 v9fs_vfs_link(struct dentry *old_dentry, struct inode *dir,
1327 	      struct dentry *dentry)
1328 {
1329 	int retval;
1330 	char name[1 + U32_MAX_DIGITS + 2]; /* sign + number + \n + \0 */
1331 	struct p9_fid *oldfid;
1332 
1333 	p9_debug(P9_DEBUG_VFS, " %lu,%pd,%pd\n",
1334 		 dir->i_ino, dentry, old_dentry);
1335 
1336 	oldfid = v9fs_fid_clone(old_dentry);
1337 	if (IS_ERR(oldfid))
1338 		return PTR_ERR(oldfid);
1339 
1340 	sprintf(name, "%d\n", oldfid->fid);
1341 	retval = v9fs_vfs_mkspecial(dir, dentry, P9_DMLINK, name);
1342 	if (!retval) {
1343 		v9fs_refresh_inode(oldfid, d_inode(old_dentry));
1344 		v9fs_invalidate_inode_attr(dir);
1345 	}
1346 	p9_client_clunk(oldfid);
1347 	return retval;
1348 }
1349 
1350 /**
1351  * v9fs_vfs_mknod - create a special file
1352  * @dir: inode destination for new link
1353  * @dentry: dentry for file
1354  * @mode: mode for creation
1355  * @rdev: device associated with special file
1356  *
1357  */
1358 
1359 static int
1360 v9fs_vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t rdev)
1361 {
1362 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
1363 	int retval;
1364 	char name[2 + U32_MAX_DIGITS + 1 + U32_MAX_DIGITS + 1];
1365 	u32 perm;
1366 
1367 	p9_debug(P9_DEBUG_VFS, " %lu,%pd mode: %hx MAJOR: %u MINOR: %u\n",
1368 		 dir->i_ino, dentry, mode,
1369 		 MAJOR(rdev), MINOR(rdev));
1370 
1371 	/* build extension */
1372 	if (S_ISBLK(mode))
1373 		sprintf(name, "b %u %u", MAJOR(rdev), MINOR(rdev));
1374 	else if (S_ISCHR(mode))
1375 		sprintf(name, "c %u %u", MAJOR(rdev), MINOR(rdev));
1376 	else
1377 		*name = 0;
1378 
1379 	perm = unixmode2p9mode(v9ses, mode);
1380 	retval = v9fs_vfs_mkspecial(dir, dentry, perm, name);
1381 
1382 	return retval;
1383 }
1384 
1385 int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode)
1386 {
1387 	int umode;
1388 	dev_t rdev;
1389 	loff_t i_size;
1390 	struct p9_wstat *st;
1391 	struct v9fs_session_info *v9ses;
1392 
1393 	v9ses = v9fs_inode2v9ses(inode);
1394 	st = p9_client_stat(fid);
1395 	if (IS_ERR(st))
1396 		return PTR_ERR(st);
1397 	/*
1398 	 * Don't update inode if the file type is different
1399 	 */
1400 	umode = p9mode2unixmode(v9ses, st, &rdev);
1401 	if ((inode->i_mode & S_IFMT) != (umode & S_IFMT))
1402 		goto out;
1403 
1404 	spin_lock(&inode->i_lock);
1405 	/*
1406 	 * We don't want to refresh inode->i_size,
1407 	 * because we may have cached data
1408 	 */
1409 	i_size = inode->i_size;
1410 	v9fs_stat2inode(st, inode, inode->i_sb);
1411 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
1412 		inode->i_size = i_size;
1413 	spin_unlock(&inode->i_lock);
1414 out:
1415 	p9stat_free(st);
1416 	kfree(st);
1417 	return 0;
1418 }
1419 
1420 static const struct inode_operations v9fs_dir_inode_operations_dotu = {
1421 	.create = v9fs_vfs_create,
1422 	.lookup = v9fs_vfs_lookup,
1423 	.atomic_open = v9fs_vfs_atomic_open,
1424 	.symlink = v9fs_vfs_symlink,
1425 	.link = v9fs_vfs_link,
1426 	.unlink = v9fs_vfs_unlink,
1427 	.mkdir = v9fs_vfs_mkdir,
1428 	.rmdir = v9fs_vfs_rmdir,
1429 	.mknod = v9fs_vfs_mknod,
1430 	.rename = v9fs_vfs_rename,
1431 	.getattr = v9fs_vfs_getattr,
1432 	.setattr = v9fs_vfs_setattr,
1433 };
1434 
1435 static const struct inode_operations v9fs_dir_inode_operations = {
1436 	.create = v9fs_vfs_create,
1437 	.lookup = v9fs_vfs_lookup,
1438 	.atomic_open = v9fs_vfs_atomic_open,
1439 	.unlink = v9fs_vfs_unlink,
1440 	.mkdir = v9fs_vfs_mkdir,
1441 	.rmdir = v9fs_vfs_rmdir,
1442 	.mknod = v9fs_vfs_mknod,
1443 	.rename = v9fs_vfs_rename,
1444 	.getattr = v9fs_vfs_getattr,
1445 	.setattr = v9fs_vfs_setattr,
1446 };
1447 
1448 static const struct inode_operations v9fs_file_inode_operations = {
1449 	.getattr = v9fs_vfs_getattr,
1450 	.setattr = v9fs_vfs_setattr,
1451 };
1452 
1453 static const struct inode_operations v9fs_symlink_inode_operations = {
1454 	.readlink = generic_readlink,
1455 	.follow_link = v9fs_vfs_follow_link,
1456 	.put_link = kfree_put_link,
1457 	.getattr = v9fs_vfs_getattr,
1458 	.setattr = v9fs_vfs_setattr,
1459 };
1460 
1461