xref: /openbmc/linux/fs/9p/vfs_inode.c (revision e8ffca61)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * This file contains vfs inode ops for the 9P2000 protocol.
4  *
5  *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
6  *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
7  */
8 
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10 
11 #include <linux/module.h>
12 #include <linux/errno.h>
13 #include <linux/fs.h>
14 #include <linux/file.h>
15 #include <linux/pagemap.h>
16 #include <linux/stat.h>
17 #include <linux/string.h>
18 #include <linux/inet.h>
19 #include <linux/namei.h>
20 #include <linux/idr.h>
21 #include <linux/sched.h>
22 #include <linux/slab.h>
23 #include <linux/xattr.h>
24 #include <linux/posix_acl.h>
25 #include <net/9p/9p.h>
26 #include <net/9p/client.h>
27 
28 #include "v9fs.h"
29 #include "v9fs_vfs.h"
30 #include "fid.h"
31 #include "cache.h"
32 #include "xattr.h"
33 #include "acl.h"
34 
35 static const struct inode_operations v9fs_dir_inode_operations;
36 static const struct inode_operations v9fs_dir_inode_operations_dotu;
37 static const struct inode_operations v9fs_file_inode_operations;
38 static const struct inode_operations v9fs_symlink_inode_operations;
39 
40 /**
41  * unixmode2p9mode - convert unix mode bits to plan 9
42  * @v9ses: v9fs session information
43  * @mode: mode to convert
44  *
45  */
46 
47 static u32 unixmode2p9mode(struct v9fs_session_info *v9ses, umode_t mode)
48 {
49 	int res;
50 
51 	res = mode & 0777;
52 	if (S_ISDIR(mode))
53 		res |= P9_DMDIR;
54 	if (v9fs_proto_dotu(v9ses)) {
55 		if (v9ses->nodev == 0) {
56 			if (S_ISSOCK(mode))
57 				res |= P9_DMSOCKET;
58 			if (S_ISFIFO(mode))
59 				res |= P9_DMNAMEDPIPE;
60 			if (S_ISBLK(mode))
61 				res |= P9_DMDEVICE;
62 			if (S_ISCHR(mode))
63 				res |= P9_DMDEVICE;
64 		}
65 
66 		if ((mode & S_ISUID) == S_ISUID)
67 			res |= P9_DMSETUID;
68 		if ((mode & S_ISGID) == S_ISGID)
69 			res |= P9_DMSETGID;
70 		if ((mode & S_ISVTX) == S_ISVTX)
71 			res |= P9_DMSETVTX;
72 	}
73 	return res;
74 }
75 
76 /**
77  * p9mode2perm- convert plan9 mode bits to unix permission bits
78  * @v9ses: v9fs session information
79  * @stat: p9_wstat from which mode need to be derived
80  *
81  */
82 static int p9mode2perm(struct v9fs_session_info *v9ses,
83 		       struct p9_wstat *stat)
84 {
85 	int res;
86 	int mode = stat->mode;
87 
88 	res = mode & S_IALLUGO;
89 	if (v9fs_proto_dotu(v9ses)) {
90 		if ((mode & P9_DMSETUID) == P9_DMSETUID)
91 			res |= S_ISUID;
92 
93 		if ((mode & P9_DMSETGID) == P9_DMSETGID)
94 			res |= S_ISGID;
95 
96 		if ((mode & P9_DMSETVTX) == P9_DMSETVTX)
97 			res |= S_ISVTX;
98 	}
99 	return res;
100 }
101 
102 /**
103  * p9mode2unixmode- convert plan9 mode bits to unix mode bits
104  * @v9ses: v9fs session information
105  * @stat: p9_wstat from which mode need to be derived
106  * @rdev: major number, minor number in case of device files.
107  *
108  */
109 static umode_t p9mode2unixmode(struct v9fs_session_info *v9ses,
110 			       struct p9_wstat *stat, dev_t *rdev)
111 {
112 	int res, r;
113 	u32 mode = stat->mode;
114 
115 	*rdev = 0;
116 	res = p9mode2perm(v9ses, stat);
117 
118 	if ((mode & P9_DMDIR) == P9_DMDIR)
119 		res |= S_IFDIR;
120 	else if ((mode & P9_DMSYMLINK) && (v9fs_proto_dotu(v9ses)))
121 		res |= S_IFLNK;
122 	else if ((mode & P9_DMSOCKET) && (v9fs_proto_dotu(v9ses))
123 		 && (v9ses->nodev == 0))
124 		res |= S_IFSOCK;
125 	else if ((mode & P9_DMNAMEDPIPE) && (v9fs_proto_dotu(v9ses))
126 		 && (v9ses->nodev == 0))
127 		res |= S_IFIFO;
128 	else if ((mode & P9_DMDEVICE) && (v9fs_proto_dotu(v9ses))
129 		 && (v9ses->nodev == 0)) {
130 		char type = 0;
131 		int major = -1, minor = -1;
132 
133 		r = sscanf(stat->extension, "%c %i %i", &type, &major, &minor);
134 		if (r != 3) {
135 			p9_debug(P9_DEBUG_ERROR,
136 				 "invalid device string, umode will be bogus: %s\n",
137 				 stat->extension);
138 			return res;
139 		}
140 		switch (type) {
141 		case 'c':
142 			res |= S_IFCHR;
143 			break;
144 		case 'b':
145 			res |= S_IFBLK;
146 			break;
147 		default:
148 			p9_debug(P9_DEBUG_ERROR, "Unknown special type %c %s\n",
149 				 type, stat->extension);
150 		}
151 		*rdev = MKDEV(major, minor);
152 	} else
153 		res |= S_IFREG;
154 
155 	return res;
156 }
157 
158 /**
159  * v9fs_uflags2omode- convert posix open flags to plan 9 mode bits
160  * @uflags: flags to convert
161  * @extended: if .u extensions are active
162  */
163 
164 int v9fs_uflags2omode(int uflags, int extended)
165 {
166 	int ret;
167 
168 	ret = 0;
169 	switch (uflags&3) {
170 	default:
171 	case O_RDONLY:
172 		ret = P9_OREAD;
173 		break;
174 
175 	case O_WRONLY:
176 		ret = P9_OWRITE;
177 		break;
178 
179 	case O_RDWR:
180 		ret = P9_ORDWR;
181 		break;
182 	}
183 
184 	if (extended) {
185 		if (uflags & O_EXCL)
186 			ret |= P9_OEXCL;
187 
188 		if (uflags & O_APPEND)
189 			ret |= P9_OAPPEND;
190 	}
191 
192 	return ret;
193 }
194 
195 /**
196  * v9fs_blank_wstat - helper function to setup a 9P stat structure
197  * @wstat: structure to initialize
198  *
199  */
200 
201 void
202 v9fs_blank_wstat(struct p9_wstat *wstat)
203 {
204 	wstat->type = ~0;
205 	wstat->dev = ~0;
206 	wstat->qid.type = ~0;
207 	wstat->qid.version = ~0;
208 	*((long long *)&wstat->qid.path) = ~0;
209 	wstat->mode = ~0;
210 	wstat->atime = ~0;
211 	wstat->mtime = ~0;
212 	wstat->length = ~0;
213 	wstat->name = NULL;
214 	wstat->uid = NULL;
215 	wstat->gid = NULL;
216 	wstat->muid = NULL;
217 	wstat->n_uid = INVALID_UID;
218 	wstat->n_gid = INVALID_GID;
219 	wstat->n_muid = INVALID_UID;
220 	wstat->extension = NULL;
221 }
222 
223 /**
224  * v9fs_alloc_inode - helper function to allocate an inode
225  * @sb: The superblock to allocate the inode from
226  */
227 struct inode *v9fs_alloc_inode(struct super_block *sb)
228 {
229 	struct v9fs_inode *v9inode;
230 
231 	v9inode = kmem_cache_alloc(v9fs_inode_cache, GFP_KERNEL);
232 	if (!v9inode)
233 		return NULL;
234 #ifdef CONFIG_9P_FSCACHE
235 	v9inode->fscache = NULL;
236 	mutex_init(&v9inode->fscache_lock);
237 #endif
238 	v9inode->writeback_fid = NULL;
239 	v9inode->cache_validity = 0;
240 	mutex_init(&v9inode->v_mutex);
241 	return &v9inode->vfs_inode;
242 }
243 
244 /**
245  * v9fs_free_inode - destroy an inode
246  * @inode: The inode to be freed
247  */
248 
249 void v9fs_free_inode(struct inode *inode)
250 {
251 	kmem_cache_free(v9fs_inode_cache, V9FS_I(inode));
252 }
253 
254 int v9fs_init_inode(struct v9fs_session_info *v9ses,
255 		    struct inode *inode, umode_t mode, dev_t rdev)
256 {
257 	int err = 0;
258 
259 	inode_init_owner(&init_user_ns, inode, NULL, mode);
260 	inode->i_blocks = 0;
261 	inode->i_rdev = rdev;
262 	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
263 	inode->i_mapping->a_ops = &v9fs_addr_operations;
264 	inode->i_private = NULL;
265 
266 	switch (mode & S_IFMT) {
267 	case S_IFIFO:
268 	case S_IFBLK:
269 	case S_IFCHR:
270 	case S_IFSOCK:
271 		if (v9fs_proto_dotl(v9ses)) {
272 			inode->i_op = &v9fs_file_inode_operations_dotl;
273 		} else if (v9fs_proto_dotu(v9ses)) {
274 			inode->i_op = &v9fs_file_inode_operations;
275 		} else {
276 			p9_debug(P9_DEBUG_ERROR,
277 				 "special files without extended mode\n");
278 			err = -EINVAL;
279 			goto error;
280 		}
281 		init_special_inode(inode, inode->i_mode, inode->i_rdev);
282 		break;
283 	case S_IFREG:
284 		if (v9fs_proto_dotl(v9ses)) {
285 			inode->i_op = &v9fs_file_inode_operations_dotl;
286 			if (v9ses->cache == CACHE_LOOSE ||
287 			    v9ses->cache == CACHE_FSCACHE)
288 				inode->i_fop =
289 					&v9fs_cached_file_operations_dotl;
290 			else if (v9ses->cache == CACHE_MMAP)
291 				inode->i_fop = &v9fs_mmap_file_operations_dotl;
292 			else
293 				inode->i_fop = &v9fs_file_operations_dotl;
294 		} else {
295 			inode->i_op = &v9fs_file_inode_operations;
296 			if (v9ses->cache == CACHE_LOOSE ||
297 			    v9ses->cache == CACHE_FSCACHE)
298 				inode->i_fop =
299 					&v9fs_cached_file_operations;
300 			else if (v9ses->cache == CACHE_MMAP)
301 				inode->i_fop = &v9fs_mmap_file_operations;
302 			else
303 				inode->i_fop = &v9fs_file_operations;
304 		}
305 
306 		break;
307 	case S_IFLNK:
308 		if (!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)) {
309 			p9_debug(P9_DEBUG_ERROR,
310 				 "extended modes used with legacy protocol\n");
311 			err = -EINVAL;
312 			goto error;
313 		}
314 
315 		if (v9fs_proto_dotl(v9ses))
316 			inode->i_op = &v9fs_symlink_inode_operations_dotl;
317 		else
318 			inode->i_op = &v9fs_symlink_inode_operations;
319 
320 		break;
321 	case S_IFDIR:
322 		inc_nlink(inode);
323 		if (v9fs_proto_dotl(v9ses))
324 			inode->i_op = &v9fs_dir_inode_operations_dotl;
325 		else if (v9fs_proto_dotu(v9ses))
326 			inode->i_op = &v9fs_dir_inode_operations_dotu;
327 		else
328 			inode->i_op = &v9fs_dir_inode_operations;
329 
330 		if (v9fs_proto_dotl(v9ses))
331 			inode->i_fop = &v9fs_dir_operations_dotl;
332 		else
333 			inode->i_fop = &v9fs_dir_operations;
334 
335 		break;
336 	default:
337 		p9_debug(P9_DEBUG_ERROR, "BAD mode 0x%hx S_IFMT 0x%x\n",
338 			 mode, mode & S_IFMT);
339 		err = -EINVAL;
340 		goto error;
341 	}
342 error:
343 	return err;
344 
345 }
346 
347 /**
348  * v9fs_get_inode - helper function to setup an inode
349  * @sb: superblock
350  * @mode: mode to setup inode with
351  * @rdev: The device numbers to set
352  */
353 
354 struct inode *v9fs_get_inode(struct super_block *sb, umode_t mode, dev_t rdev)
355 {
356 	int err;
357 	struct inode *inode;
358 	struct v9fs_session_info *v9ses = sb->s_fs_info;
359 
360 	p9_debug(P9_DEBUG_VFS, "super block: %p mode: %ho\n", sb, mode);
361 
362 	inode = new_inode(sb);
363 	if (!inode) {
364 		pr_warn("%s (%d): Problem allocating inode\n",
365 			__func__, task_pid_nr(current));
366 		return ERR_PTR(-ENOMEM);
367 	}
368 	err = v9fs_init_inode(v9ses, inode, mode, rdev);
369 	if (err) {
370 		iput(inode);
371 		return ERR_PTR(err);
372 	}
373 	return inode;
374 }
375 
376 /**
377  * v9fs_evict_inode - Remove an inode from the inode cache
378  * @inode: inode to release
379  *
380  */
381 void v9fs_evict_inode(struct inode *inode)
382 {
383 	struct v9fs_inode *v9inode = V9FS_I(inode);
384 
385 	truncate_inode_pages_final(&inode->i_data);
386 	clear_inode(inode);
387 	filemap_fdatawrite(&inode->i_data);
388 
389 	v9fs_cache_inode_put_cookie(inode);
390 	/* clunk the fid stashed in writeback_fid */
391 	if (v9inode->writeback_fid) {
392 		p9_client_clunk(v9inode->writeback_fid);
393 		v9inode->writeback_fid = NULL;
394 	}
395 }
396 
397 static int v9fs_test_inode(struct inode *inode, void *data)
398 {
399 	int umode;
400 	dev_t rdev;
401 	struct v9fs_inode *v9inode = V9FS_I(inode);
402 	struct p9_wstat *st = (struct p9_wstat *)data;
403 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
404 
405 	umode = p9mode2unixmode(v9ses, st, &rdev);
406 	/* don't match inode of different type */
407 	if (inode_wrong_type(inode, umode))
408 		return 0;
409 
410 	/* compare qid details */
411 	if (memcmp(&v9inode->qid.version,
412 		   &st->qid.version, sizeof(v9inode->qid.version)))
413 		return 0;
414 
415 	if (v9inode->qid.type != st->qid.type)
416 		return 0;
417 
418 	if (v9inode->qid.path != st->qid.path)
419 		return 0;
420 	return 1;
421 }
422 
423 static int v9fs_test_new_inode(struct inode *inode, void *data)
424 {
425 	return 0;
426 }
427 
428 static int v9fs_set_inode(struct inode *inode,  void *data)
429 {
430 	struct v9fs_inode *v9inode = V9FS_I(inode);
431 	struct p9_wstat *st = (struct p9_wstat *)data;
432 
433 	memcpy(&v9inode->qid, &st->qid, sizeof(st->qid));
434 	return 0;
435 }
436 
437 static struct inode *v9fs_qid_iget(struct super_block *sb,
438 				   struct p9_qid *qid,
439 				   struct p9_wstat *st,
440 				   int new)
441 {
442 	dev_t rdev;
443 	int retval;
444 	umode_t umode;
445 	unsigned long i_ino;
446 	struct inode *inode;
447 	struct v9fs_session_info *v9ses = sb->s_fs_info;
448 	int (*test)(struct inode *inode, void *data);
449 
450 	if (new)
451 		test = v9fs_test_new_inode;
452 	else
453 		test = v9fs_test_inode;
454 
455 	i_ino = v9fs_qid2ino(qid);
456 	inode = iget5_locked(sb, i_ino, test, v9fs_set_inode, st);
457 	if (!inode)
458 		return ERR_PTR(-ENOMEM);
459 	if (!(inode->i_state & I_NEW))
460 		return inode;
461 	/*
462 	 * initialize the inode with the stat info
463 	 * FIXME!! we may need support for stale inodes
464 	 * later.
465 	 */
466 	inode->i_ino = i_ino;
467 	umode = p9mode2unixmode(v9ses, st, &rdev);
468 	retval = v9fs_init_inode(v9ses, inode, umode, rdev);
469 	if (retval)
470 		goto error;
471 
472 	v9fs_stat2inode(st, inode, sb, 0);
473 	v9fs_cache_inode_get_cookie(inode);
474 	unlock_new_inode(inode);
475 	return inode;
476 error:
477 	iget_failed(inode);
478 	return ERR_PTR(retval);
479 
480 }
481 
482 struct inode *
483 v9fs_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
484 		    struct super_block *sb, int new)
485 {
486 	struct p9_wstat *st;
487 	struct inode *inode = NULL;
488 
489 	st = p9_client_stat(fid);
490 	if (IS_ERR(st))
491 		return ERR_CAST(st);
492 
493 	inode = v9fs_qid_iget(sb, &st->qid, st, new);
494 	p9stat_free(st);
495 	kfree(st);
496 	return inode;
497 }
498 
499 /**
500  * v9fs_at_to_dotl_flags- convert Linux specific AT flags to
501  * plan 9 AT flag.
502  * @flags: flags to convert
503  */
504 static int v9fs_at_to_dotl_flags(int flags)
505 {
506 	int rflags = 0;
507 
508 	if (flags & AT_REMOVEDIR)
509 		rflags |= P9_DOTL_AT_REMOVEDIR;
510 
511 	return rflags;
512 }
513 
514 /**
515  * v9fs_dec_count - helper functon to drop i_nlink.
516  *
517  * If a directory had nlink <= 2 (including . and ..), then we should not drop
518  * the link count, which indicates the underlying exported fs doesn't maintain
519  * nlink accurately. e.g.
520  * - overlayfs sets nlink to 1 for merged dir
521  * - ext4 (with dir_nlink feature enabled) sets nlink to 1 if a dir has more
522  *   than EXT4_LINK_MAX (65000) links.
523  *
524  * @inode: inode whose nlink is being dropped
525  */
526 static void v9fs_dec_count(struct inode *inode)
527 {
528 	if (!S_ISDIR(inode->i_mode) || inode->i_nlink > 2)
529 		drop_nlink(inode);
530 }
531 
532 /**
533  * v9fs_remove - helper function to remove files and directories
534  * @dir: directory inode that is being deleted
535  * @dentry:  dentry that is being deleted
536  * @flags: removing a directory
537  *
538  */
539 
540 static int v9fs_remove(struct inode *dir, struct dentry *dentry, int flags)
541 {
542 	struct inode *inode;
543 	int retval = -EOPNOTSUPP;
544 	struct p9_fid *v9fid, *dfid;
545 	struct v9fs_session_info *v9ses;
546 
547 	p9_debug(P9_DEBUG_VFS, "inode: %p dentry: %p rmdir: %x\n",
548 		 dir, dentry, flags);
549 
550 	v9ses = v9fs_inode2v9ses(dir);
551 	inode = d_inode(dentry);
552 	dfid = v9fs_parent_fid(dentry);
553 	if (IS_ERR(dfid)) {
554 		retval = PTR_ERR(dfid);
555 		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", retval);
556 		return retval;
557 	}
558 	if (v9fs_proto_dotl(v9ses))
559 		retval = p9_client_unlinkat(dfid, dentry->d_name.name,
560 					    v9fs_at_to_dotl_flags(flags));
561 	p9_client_clunk(dfid);
562 	if (retval == -EOPNOTSUPP) {
563 		/* Try the one based on path */
564 		v9fid = v9fs_fid_clone(dentry);
565 		if (IS_ERR(v9fid))
566 			return PTR_ERR(v9fid);
567 		retval = p9_client_remove(v9fid);
568 	}
569 	if (!retval) {
570 		/*
571 		 * directories on unlink should have zero
572 		 * link count
573 		 */
574 		if (flags & AT_REMOVEDIR) {
575 			clear_nlink(inode);
576 			v9fs_dec_count(dir);
577 		} else
578 			v9fs_dec_count(inode);
579 
580 		v9fs_invalidate_inode_attr(inode);
581 		v9fs_invalidate_inode_attr(dir);
582 
583 		/* invalidate all fids associated with dentry */
584 		/* NOTE: This will not include open fids */
585 		dentry->d_op->d_release(dentry);
586 	}
587 	return retval;
588 }
589 
590 /**
591  * v9fs_create - Create a file
592  * @v9ses: session information
593  * @dir: directory that dentry is being created in
594  * @dentry:  dentry that is being created
595  * @extension: 9p2000.u extension string to support devices, etc.
596  * @perm: create permissions
597  * @mode: open mode
598  *
599  */
600 static struct p9_fid *
601 v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
602 		struct dentry *dentry, char *extension, u32 perm, u8 mode)
603 {
604 	int err;
605 	const unsigned char *name;
606 	struct p9_fid *dfid, *ofid = NULL, *fid = NULL;
607 	struct inode *inode;
608 
609 	p9_debug(P9_DEBUG_VFS, "name %pd\n", dentry);
610 
611 	err = 0;
612 	name = dentry->d_name.name;
613 	dfid = v9fs_parent_fid(dentry);
614 	if (IS_ERR(dfid)) {
615 		err = PTR_ERR(dfid);
616 		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", err);
617 		return ERR_PTR(err);
618 	}
619 
620 	/* clone a fid to use for creation */
621 	ofid = clone_fid(dfid);
622 	if (IS_ERR(ofid)) {
623 		err = PTR_ERR(ofid);
624 		p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n", err);
625 		p9_client_clunk(dfid);
626 		return ERR_PTR(err);
627 	}
628 
629 	err = p9_client_fcreate(ofid, name, perm, mode, extension);
630 	if (err < 0) {
631 		p9_debug(P9_DEBUG_VFS, "p9_client_fcreate failed %d\n", err);
632 		p9_client_clunk(dfid);
633 		goto error;
634 	}
635 
636 	if (!(perm & P9_DMLINK)) {
637 		/* now walk from the parent so we can get unopened fid */
638 		fid = p9_client_walk(dfid, 1, &name, 1);
639 		if (IS_ERR(fid)) {
640 			err = PTR_ERR(fid);
641 			p9_debug(P9_DEBUG_VFS,
642 				   "p9_client_walk failed %d\n", err);
643 			fid = NULL;
644 			p9_client_clunk(dfid);
645 			goto error;
646 		}
647 		/*
648 		 * instantiate inode and assign the unopened fid to the dentry
649 		 */
650 		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
651 		if (IS_ERR(inode)) {
652 			err = PTR_ERR(inode);
653 			p9_debug(P9_DEBUG_VFS,
654 				   "inode creation failed %d\n", err);
655 			p9_client_clunk(dfid);
656 			goto error;
657 		}
658 		v9fs_fid_add(dentry, fid);
659 		d_instantiate(dentry, inode);
660 	}
661 	p9_client_clunk(dfid);
662 	return ofid;
663 error:
664 	if (ofid)
665 		p9_client_clunk(ofid);
666 
667 	if (fid)
668 		p9_client_clunk(fid);
669 
670 	return ERR_PTR(err);
671 }
672 
673 /**
674  * v9fs_vfs_create - VFS hook to create a regular file
675  * @mnt_userns: The user namespace of the mount
676  * @dir: The parent directory
677  * @dentry: The name of file to be created
678  * @mode: The UNIX file mode to set
679  * @excl: True if the file must not yet exist
680  *
681  * open(.., O_CREAT) is handled in v9fs_vfs_atomic_open().  This is only called
682  * for mknod(2).
683  *
684  */
685 
686 static int
687 v9fs_vfs_create(struct user_namespace *mnt_userns, struct inode *dir,
688 		struct dentry *dentry, umode_t mode, bool excl)
689 {
690 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
691 	u32 perm = unixmode2p9mode(v9ses, mode);
692 	struct p9_fid *fid;
693 
694 	/* P9_OEXCL? */
695 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_ORDWR);
696 	if (IS_ERR(fid))
697 		return PTR_ERR(fid);
698 
699 	v9fs_invalidate_inode_attr(dir);
700 	p9_client_clunk(fid);
701 
702 	return 0;
703 }
704 
705 /**
706  * v9fs_vfs_mkdir - VFS mkdir hook to create a directory
707  * @mnt_userns: The user namespace of the mount
708  * @dir:  inode that is being unlinked
709  * @dentry: dentry that is being unlinked
710  * @mode: mode for new directory
711  *
712  */
713 
714 static int v9fs_vfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
715 			  struct dentry *dentry, umode_t mode)
716 {
717 	int err;
718 	u32 perm;
719 	struct p9_fid *fid;
720 	struct v9fs_session_info *v9ses;
721 
722 	p9_debug(P9_DEBUG_VFS, "name %pd\n", dentry);
723 	err = 0;
724 	v9ses = v9fs_inode2v9ses(dir);
725 	perm = unixmode2p9mode(v9ses, mode | S_IFDIR);
726 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_OREAD);
727 	if (IS_ERR(fid)) {
728 		err = PTR_ERR(fid);
729 		fid = NULL;
730 	} else {
731 		inc_nlink(dir);
732 		v9fs_invalidate_inode_attr(dir);
733 	}
734 
735 	if (fid)
736 		p9_client_clunk(fid);
737 
738 	return err;
739 }
740 
741 /**
742  * v9fs_vfs_lookup - VFS lookup hook to "walk" to a new inode
743  * @dir:  inode that is being walked from
744  * @dentry: dentry that is being walked to?
745  * @flags: lookup flags (unused)
746  *
747  */
748 
749 struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
750 				      unsigned int flags)
751 {
752 	struct dentry *res;
753 	struct v9fs_session_info *v9ses;
754 	struct p9_fid *dfid, *fid;
755 	struct inode *inode;
756 	const unsigned char *name;
757 
758 	p9_debug(P9_DEBUG_VFS, "dir: %p dentry: (%pd) %p flags: %x\n",
759 		 dir, dentry, dentry, flags);
760 
761 	if (dentry->d_name.len > NAME_MAX)
762 		return ERR_PTR(-ENAMETOOLONG);
763 
764 	v9ses = v9fs_inode2v9ses(dir);
765 	/* We can walk d_parent because we hold the dir->i_mutex */
766 	dfid = v9fs_parent_fid(dentry);
767 	if (IS_ERR(dfid))
768 		return ERR_CAST(dfid);
769 
770 	/*
771 	 * Make sure we don't use a wrong inode due to parallel
772 	 * unlink. For cached mode create calls request for new
773 	 * inode. But with cache disabled, lookup should do this.
774 	 */
775 	name = dentry->d_name.name;
776 	fid = p9_client_walk(dfid, 1, &name, 1);
777 	p9_client_clunk(dfid);
778 	if (fid == ERR_PTR(-ENOENT))
779 		inode = NULL;
780 	else if (IS_ERR(fid))
781 		inode = ERR_CAST(fid);
782 	else if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
783 		inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
784 	else
785 		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
786 	/*
787 	 * If we had a rename on the server and a parallel lookup
788 	 * for the new name, then make sure we instantiate with
789 	 * the new name. ie look up for a/b, while on server somebody
790 	 * moved b under k and client parallely did a lookup for
791 	 * k/b.
792 	 */
793 	res = d_splice_alias(inode, dentry);
794 	if (!IS_ERR(fid)) {
795 		if (!res)
796 			v9fs_fid_add(dentry, fid);
797 		else if (!IS_ERR(res))
798 			v9fs_fid_add(res, fid);
799 		else
800 			p9_client_clunk(fid);
801 	}
802 	return res;
803 }
804 
805 static int
806 v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
807 		     struct file *file, unsigned int flags, umode_t mode)
808 {
809 	int err;
810 	u32 perm;
811 	struct v9fs_inode *v9inode;
812 	struct v9fs_session_info *v9ses;
813 	struct p9_fid *fid, *inode_fid;
814 	struct dentry *res = NULL;
815 	struct inode *inode;
816 
817 	if (d_in_lookup(dentry)) {
818 		res = v9fs_vfs_lookup(dir, dentry, 0);
819 		if (IS_ERR(res))
820 			return PTR_ERR(res);
821 
822 		if (res)
823 			dentry = res;
824 	}
825 
826 	/* Only creates */
827 	if (!(flags & O_CREAT) || d_really_is_positive(dentry))
828 		return finish_no_open(file, res);
829 
830 	err = 0;
831 
832 	v9ses = v9fs_inode2v9ses(dir);
833 	perm = unixmode2p9mode(v9ses, mode);
834 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm,
835 				v9fs_uflags2omode(flags,
836 						v9fs_proto_dotu(v9ses)));
837 	if (IS_ERR(fid)) {
838 		err = PTR_ERR(fid);
839 		fid = NULL;
840 		goto error;
841 	}
842 
843 	v9fs_invalidate_inode_attr(dir);
844 	inode = d_inode(dentry);
845 	v9inode = V9FS_I(inode);
846 	mutex_lock(&v9inode->v_mutex);
847 	if ((v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) &&
848 	    !v9inode->writeback_fid &&
849 	    ((flags & O_ACCMODE) != O_RDONLY)) {
850 		/*
851 		 * clone a fid and add it to writeback_fid
852 		 * we do it during open time instead of
853 		 * page dirty time via write_begin/page_mkwrite
854 		 * because we want write after unlink usecase
855 		 * to work.
856 		 */
857 		inode_fid = v9fs_writeback_fid(dentry);
858 		if (IS_ERR(inode_fid)) {
859 			err = PTR_ERR(inode_fid);
860 			mutex_unlock(&v9inode->v_mutex);
861 			goto error;
862 		}
863 		v9inode->writeback_fid = (void *) inode_fid;
864 	}
865 	mutex_unlock(&v9inode->v_mutex);
866 	err = finish_open(file, dentry, generic_file_open);
867 	if (err)
868 		goto error;
869 
870 	file->private_data = fid;
871 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
872 		v9fs_cache_inode_set_cookie(d_inode(dentry), file);
873 	v9fs_open_fid_add(inode, fid);
874 
875 	file->f_mode |= FMODE_CREATED;
876 out:
877 	dput(res);
878 	return err;
879 
880 error:
881 	if (fid)
882 		p9_client_clunk(fid);
883 	goto out;
884 }
885 
886 /**
887  * v9fs_vfs_unlink - VFS unlink hook to delete an inode
888  * @i:  inode that is being unlinked
889  * @d: dentry that is being unlinked
890  *
891  */
892 
893 int v9fs_vfs_unlink(struct inode *i, struct dentry *d)
894 {
895 	return v9fs_remove(i, d, 0);
896 }
897 
898 /**
899  * v9fs_vfs_rmdir - VFS unlink hook to delete a directory
900  * @i:  inode that is being unlinked
901  * @d: dentry that is being unlinked
902  *
903  */
904 
905 int v9fs_vfs_rmdir(struct inode *i, struct dentry *d)
906 {
907 	return v9fs_remove(i, d, AT_REMOVEDIR);
908 }
909 
910 /**
911  * v9fs_vfs_rename - VFS hook to rename an inode
912  * @mnt_userns: The user namespace of the mount
913  * @old_dir:  old dir inode
914  * @old_dentry: old dentry
915  * @new_dir: new dir inode
916  * @new_dentry: new dentry
917  * @flags: RENAME_* flags
918  *
919  */
920 
921 int
922 v9fs_vfs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
923 		struct dentry *old_dentry, struct inode *new_dir,
924 		struct dentry *new_dentry, unsigned int flags)
925 {
926 	int retval;
927 	struct inode *old_inode;
928 	struct inode *new_inode;
929 	struct v9fs_session_info *v9ses;
930 	struct p9_fid *oldfid, *dfid;
931 	struct p9_fid *olddirfid;
932 	struct p9_fid *newdirfid;
933 	struct p9_wstat wstat;
934 
935 	if (flags)
936 		return -EINVAL;
937 
938 	p9_debug(P9_DEBUG_VFS, "\n");
939 	retval = 0;
940 	old_inode = d_inode(old_dentry);
941 	new_inode = d_inode(new_dentry);
942 	v9ses = v9fs_inode2v9ses(old_inode);
943 	oldfid = v9fs_fid_lookup(old_dentry);
944 	if (IS_ERR(oldfid))
945 		return PTR_ERR(oldfid);
946 
947 	dfid = v9fs_parent_fid(old_dentry);
948 	olddirfid = clone_fid(dfid);
949 	if (dfid && !IS_ERR(dfid))
950 		p9_client_clunk(dfid);
951 
952 	if (IS_ERR(olddirfid)) {
953 		retval = PTR_ERR(olddirfid);
954 		goto done;
955 	}
956 
957 	dfid = v9fs_parent_fid(new_dentry);
958 	newdirfid = clone_fid(dfid);
959 	p9_client_clunk(dfid);
960 
961 	if (IS_ERR(newdirfid)) {
962 		retval = PTR_ERR(newdirfid);
963 		goto clunk_olddir;
964 	}
965 
966 	down_write(&v9ses->rename_sem);
967 	if (v9fs_proto_dotl(v9ses)) {
968 		retval = p9_client_renameat(olddirfid, old_dentry->d_name.name,
969 					    newdirfid, new_dentry->d_name.name);
970 		if (retval == -EOPNOTSUPP)
971 			retval = p9_client_rename(oldfid, newdirfid,
972 						  new_dentry->d_name.name);
973 		if (retval != -EOPNOTSUPP)
974 			goto clunk_newdir;
975 	}
976 	if (old_dentry->d_parent != new_dentry->d_parent) {
977 		/*
978 		 * 9P .u can only handle file rename in the same directory
979 		 */
980 
981 		p9_debug(P9_DEBUG_ERROR, "old dir and new dir are different\n");
982 		retval = -EXDEV;
983 		goto clunk_newdir;
984 	}
985 	v9fs_blank_wstat(&wstat);
986 	wstat.muid = v9ses->uname;
987 	wstat.name = new_dentry->d_name.name;
988 	retval = p9_client_wstat(oldfid, &wstat);
989 
990 clunk_newdir:
991 	if (!retval) {
992 		if (new_inode) {
993 			if (S_ISDIR(new_inode->i_mode))
994 				clear_nlink(new_inode);
995 			else
996 				v9fs_dec_count(new_inode);
997 		}
998 		if (S_ISDIR(old_inode->i_mode)) {
999 			if (!new_inode)
1000 				inc_nlink(new_dir);
1001 			v9fs_dec_count(old_dir);
1002 		}
1003 		v9fs_invalidate_inode_attr(old_inode);
1004 		v9fs_invalidate_inode_attr(old_dir);
1005 		v9fs_invalidate_inode_attr(new_dir);
1006 
1007 		/* successful rename */
1008 		d_move(old_dentry, new_dentry);
1009 	}
1010 	up_write(&v9ses->rename_sem);
1011 	p9_client_clunk(newdirfid);
1012 
1013 clunk_olddir:
1014 	p9_client_clunk(olddirfid);
1015 
1016 done:
1017 	p9_client_clunk(oldfid);
1018 	return retval;
1019 }
1020 
1021 /**
1022  * v9fs_vfs_getattr - retrieve file metadata
1023  * @mnt_userns: The user namespace of the mount
1024  * @path: Object to query
1025  * @stat: metadata structure to populate
1026  * @request_mask: Mask of STATX_xxx flags indicating the caller's interests
1027  * @flags: AT_STATX_xxx setting
1028  *
1029  */
1030 
1031 static int
1032 v9fs_vfs_getattr(struct user_namespace *mnt_userns, const struct path *path,
1033 		 struct kstat *stat, u32 request_mask, unsigned int flags)
1034 {
1035 	struct dentry *dentry = path->dentry;
1036 	struct v9fs_session_info *v9ses;
1037 	struct p9_fid *fid;
1038 	struct p9_wstat *st;
1039 
1040 	p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
1041 	v9ses = v9fs_dentry2v9ses(dentry);
1042 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
1043 		generic_fillattr(&init_user_ns, d_inode(dentry), stat);
1044 		return 0;
1045 	}
1046 	fid = v9fs_fid_lookup(dentry);
1047 	if (IS_ERR(fid))
1048 		return PTR_ERR(fid);
1049 
1050 	st = p9_client_stat(fid);
1051 	p9_client_clunk(fid);
1052 	if (IS_ERR(st))
1053 		return PTR_ERR(st);
1054 
1055 	v9fs_stat2inode(st, d_inode(dentry), dentry->d_sb, 0);
1056 	generic_fillattr(&init_user_ns, d_inode(dentry), stat);
1057 
1058 	p9stat_free(st);
1059 	kfree(st);
1060 	return 0;
1061 }
1062 
1063 /**
1064  * v9fs_vfs_setattr - set file metadata
1065  * @mnt_userns: The user namespace of the mount
1066  * @dentry: file whose metadata to set
1067  * @iattr: metadata assignment structure
1068  *
1069  */
1070 
1071 static int v9fs_vfs_setattr(struct user_namespace *mnt_userns,
1072 			    struct dentry *dentry, struct iattr *iattr)
1073 {
1074 	int retval, use_dentry = 0;
1075 	struct v9fs_session_info *v9ses;
1076 	struct p9_fid *fid = NULL;
1077 	struct p9_wstat wstat;
1078 
1079 	p9_debug(P9_DEBUG_VFS, "\n");
1080 	retval = setattr_prepare(&init_user_ns, dentry, iattr);
1081 	if (retval)
1082 		return retval;
1083 
1084 	retval = -EPERM;
1085 	v9ses = v9fs_dentry2v9ses(dentry);
1086 	if (iattr->ia_valid & ATTR_FILE) {
1087 		fid = iattr->ia_file->private_data;
1088 		WARN_ON(!fid);
1089 	}
1090 	if (!fid) {
1091 		fid = v9fs_fid_lookup(dentry);
1092 		use_dentry = 1;
1093 	}
1094 	if (IS_ERR(fid))
1095 		return PTR_ERR(fid);
1096 
1097 	v9fs_blank_wstat(&wstat);
1098 	if (iattr->ia_valid & ATTR_MODE)
1099 		wstat.mode = unixmode2p9mode(v9ses, iattr->ia_mode);
1100 
1101 	if (iattr->ia_valid & ATTR_MTIME)
1102 		wstat.mtime = iattr->ia_mtime.tv_sec;
1103 
1104 	if (iattr->ia_valid & ATTR_ATIME)
1105 		wstat.atime = iattr->ia_atime.tv_sec;
1106 
1107 	if (iattr->ia_valid & ATTR_SIZE)
1108 		wstat.length = iattr->ia_size;
1109 
1110 	if (v9fs_proto_dotu(v9ses)) {
1111 		if (iattr->ia_valid & ATTR_UID)
1112 			wstat.n_uid = iattr->ia_uid;
1113 
1114 		if (iattr->ia_valid & ATTR_GID)
1115 			wstat.n_gid = iattr->ia_gid;
1116 	}
1117 
1118 	/* Write all dirty data */
1119 	if (d_is_reg(dentry))
1120 		filemap_write_and_wait(d_inode(dentry)->i_mapping);
1121 
1122 	retval = p9_client_wstat(fid, &wstat);
1123 
1124 	if (use_dentry)
1125 		p9_client_clunk(fid);
1126 
1127 	if (retval < 0)
1128 		return retval;
1129 
1130 	if ((iattr->ia_valid & ATTR_SIZE) &&
1131 	    iattr->ia_size != i_size_read(d_inode(dentry)))
1132 		truncate_setsize(d_inode(dentry), iattr->ia_size);
1133 
1134 	v9fs_invalidate_inode_attr(d_inode(dentry));
1135 
1136 	setattr_copy(&init_user_ns, d_inode(dentry), iattr);
1137 	mark_inode_dirty(d_inode(dentry));
1138 	return 0;
1139 }
1140 
1141 /**
1142  * v9fs_stat2inode - populate an inode structure with mistat info
1143  * @stat: Plan 9 metadata (mistat) structure
1144  * @inode: inode to populate
1145  * @sb: superblock of filesystem
1146  * @flags: control flags (e.g. V9FS_STAT2INODE_KEEP_ISIZE)
1147  *
1148  */
1149 
1150 void
1151 v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
1152 		 struct super_block *sb, unsigned int flags)
1153 {
1154 	umode_t mode;
1155 	struct v9fs_session_info *v9ses = sb->s_fs_info;
1156 	struct v9fs_inode *v9inode = V9FS_I(inode);
1157 
1158 	set_nlink(inode, 1);
1159 
1160 	inode->i_atime.tv_sec = stat->atime;
1161 	inode->i_mtime.tv_sec = stat->mtime;
1162 	inode->i_ctime.tv_sec = stat->mtime;
1163 
1164 	inode->i_uid = v9ses->dfltuid;
1165 	inode->i_gid = v9ses->dfltgid;
1166 
1167 	if (v9fs_proto_dotu(v9ses)) {
1168 		inode->i_uid = stat->n_uid;
1169 		inode->i_gid = stat->n_gid;
1170 	}
1171 	if ((S_ISREG(inode->i_mode)) || (S_ISDIR(inode->i_mode))) {
1172 		if (v9fs_proto_dotu(v9ses)) {
1173 			unsigned int i_nlink;
1174 			/*
1175 			 * Hadlink support got added later to the .u extension.
1176 			 * So there can be a server out there that doesn't
1177 			 * support this even with .u extension. That would
1178 			 * just leave us with stat->extension being an empty
1179 			 * string, though.
1180 			 */
1181 			/* HARDLINKCOUNT %u */
1182 			if (sscanf(stat->extension,
1183 				   " HARDLINKCOUNT %u", &i_nlink) == 1)
1184 				set_nlink(inode, i_nlink);
1185 		}
1186 	}
1187 	mode = p9mode2perm(v9ses, stat);
1188 	mode |= inode->i_mode & ~S_IALLUGO;
1189 	inode->i_mode = mode;
1190 
1191 	if (!(flags & V9FS_STAT2INODE_KEEP_ISIZE))
1192 		v9fs_i_size_write(inode, stat->length);
1193 	/* not real number of blocks, but 512 byte ones ... */
1194 	inode->i_blocks = (stat->length + 512 - 1) >> 9;
1195 	v9inode->cache_validity &= ~V9FS_INO_INVALID_ATTR;
1196 }
1197 
1198 /**
1199  * v9fs_qid2ino - convert qid into inode number
1200  * @qid: qid to hash
1201  *
1202  * BUG: potential for inode number collisions?
1203  */
1204 
1205 ino_t v9fs_qid2ino(struct p9_qid *qid)
1206 {
1207 	u64 path = qid->path + 2;
1208 	ino_t i = 0;
1209 
1210 	if (sizeof(ino_t) == sizeof(path))
1211 		memcpy(&i, &path, sizeof(ino_t));
1212 	else
1213 		i = (ino_t) (path ^ (path >> 32));
1214 
1215 	return i;
1216 }
1217 
1218 /**
1219  * v9fs_vfs_get_link - follow a symlink path
1220  * @dentry: dentry for symlink
1221  * @inode: inode for symlink
1222  * @done: delayed call for when we are done with the return value
1223  */
1224 
1225 static const char *v9fs_vfs_get_link(struct dentry *dentry,
1226 				     struct inode *inode,
1227 				     struct delayed_call *done)
1228 {
1229 	struct v9fs_session_info *v9ses;
1230 	struct p9_fid *fid;
1231 	struct p9_wstat *st;
1232 	char *res;
1233 
1234 	if (!dentry)
1235 		return ERR_PTR(-ECHILD);
1236 
1237 	v9ses = v9fs_dentry2v9ses(dentry);
1238 	fid = v9fs_fid_lookup(dentry);
1239 	p9_debug(P9_DEBUG_VFS, "%pd\n", dentry);
1240 
1241 	if (IS_ERR(fid))
1242 		return ERR_CAST(fid);
1243 
1244 	if (!v9fs_proto_dotu(v9ses))
1245 		return ERR_PTR(-EBADF);
1246 
1247 	st = p9_client_stat(fid);
1248 	p9_client_clunk(fid);
1249 	if (IS_ERR(st))
1250 		return ERR_CAST(st);
1251 
1252 	if (!(st->mode & P9_DMSYMLINK)) {
1253 		p9stat_free(st);
1254 		kfree(st);
1255 		return ERR_PTR(-EINVAL);
1256 	}
1257 	res = st->extension;
1258 	st->extension = NULL;
1259 	if (strlen(res) >= PATH_MAX)
1260 		res[PATH_MAX - 1] = '\0';
1261 
1262 	p9stat_free(st);
1263 	kfree(st);
1264 	set_delayed_call(done, kfree_link, res);
1265 	return res;
1266 }
1267 
1268 /**
1269  * v9fs_vfs_mkspecial - create a special file
1270  * @dir: inode to create special file in
1271  * @dentry: dentry to create
1272  * @perm: mode to create special file
1273  * @extension: 9p2000.u format extension string representing special file
1274  *
1275  */
1276 
1277 static int v9fs_vfs_mkspecial(struct inode *dir, struct dentry *dentry,
1278 	u32 perm, const char *extension)
1279 {
1280 	struct p9_fid *fid;
1281 	struct v9fs_session_info *v9ses;
1282 
1283 	v9ses = v9fs_inode2v9ses(dir);
1284 	if (!v9fs_proto_dotu(v9ses)) {
1285 		p9_debug(P9_DEBUG_ERROR, "not extended\n");
1286 		return -EPERM;
1287 	}
1288 
1289 	fid = v9fs_create(v9ses, dir, dentry, (char *) extension, perm,
1290 								P9_OREAD);
1291 	if (IS_ERR(fid))
1292 		return PTR_ERR(fid);
1293 
1294 	v9fs_invalidate_inode_attr(dir);
1295 	p9_client_clunk(fid);
1296 	return 0;
1297 }
1298 
1299 /**
1300  * v9fs_vfs_symlink - helper function to create symlinks
1301  * @mnt_userns: The user namespace of the mount
1302  * @dir: directory inode containing symlink
1303  * @dentry: dentry for symlink
1304  * @symname: symlink data
1305  *
1306  * See Also: 9P2000.u RFC for more information
1307  *
1308  */
1309 
1310 static int
1311 v9fs_vfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
1312 		 struct dentry *dentry, const char *symname)
1313 {
1314 	p9_debug(P9_DEBUG_VFS, " %lu,%pd,%s\n",
1315 		 dir->i_ino, dentry, symname);
1316 
1317 	return v9fs_vfs_mkspecial(dir, dentry, P9_DMSYMLINK, symname);
1318 }
1319 
1320 #define U32_MAX_DIGITS 10
1321 
1322 /**
1323  * v9fs_vfs_link - create a hardlink
1324  * @old_dentry: dentry for file to link to
1325  * @dir: inode destination for new link
1326  * @dentry: dentry for link
1327  *
1328  */
1329 
1330 static int
1331 v9fs_vfs_link(struct dentry *old_dentry, struct inode *dir,
1332 	      struct dentry *dentry)
1333 {
1334 	int retval;
1335 	char name[1 + U32_MAX_DIGITS + 2]; /* sign + number + \n + \0 */
1336 	struct p9_fid *oldfid;
1337 
1338 	p9_debug(P9_DEBUG_VFS, " %lu,%pd,%pd\n",
1339 		 dir->i_ino, dentry, old_dentry);
1340 
1341 	oldfid = v9fs_fid_clone(old_dentry);
1342 	if (IS_ERR(oldfid))
1343 		return PTR_ERR(oldfid);
1344 
1345 	sprintf(name, "%d\n", oldfid->fid);
1346 	retval = v9fs_vfs_mkspecial(dir, dentry, P9_DMLINK, name);
1347 	if (!retval) {
1348 		v9fs_refresh_inode(oldfid, d_inode(old_dentry));
1349 		v9fs_invalidate_inode_attr(dir);
1350 	}
1351 	p9_client_clunk(oldfid);
1352 	return retval;
1353 }
1354 
1355 /**
1356  * v9fs_vfs_mknod - create a special file
1357  * @mnt_userns: The user namespace of the mount
1358  * @dir: inode destination for new link
1359  * @dentry: dentry for file
1360  * @mode: mode for creation
1361  * @rdev: device associated with special file
1362  *
1363  */
1364 
1365 static int
1366 v9fs_vfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
1367 	       struct dentry *dentry, umode_t mode, dev_t rdev)
1368 {
1369 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
1370 	int retval;
1371 	char name[2 + U32_MAX_DIGITS + 1 + U32_MAX_DIGITS + 1];
1372 	u32 perm;
1373 
1374 	p9_debug(P9_DEBUG_VFS, " %lu,%pd mode: %x MAJOR: %u MINOR: %u\n",
1375 		 dir->i_ino, dentry, mode,
1376 		 MAJOR(rdev), MINOR(rdev));
1377 
1378 	/* build extension */
1379 	if (S_ISBLK(mode))
1380 		sprintf(name, "b %u %u", MAJOR(rdev), MINOR(rdev));
1381 	else if (S_ISCHR(mode))
1382 		sprintf(name, "c %u %u", MAJOR(rdev), MINOR(rdev));
1383 	else
1384 		*name = 0;
1385 
1386 	perm = unixmode2p9mode(v9ses, mode);
1387 	retval = v9fs_vfs_mkspecial(dir, dentry, perm, name);
1388 
1389 	return retval;
1390 }
1391 
1392 int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode)
1393 {
1394 	int umode;
1395 	dev_t rdev;
1396 	struct p9_wstat *st;
1397 	struct v9fs_session_info *v9ses;
1398 	unsigned int flags;
1399 
1400 	v9ses = v9fs_inode2v9ses(inode);
1401 	st = p9_client_stat(fid);
1402 	if (IS_ERR(st))
1403 		return PTR_ERR(st);
1404 	/*
1405 	 * Don't update inode if the file type is different
1406 	 */
1407 	umode = p9mode2unixmode(v9ses, st, &rdev);
1408 	if (inode_wrong_type(inode, umode))
1409 		goto out;
1410 
1411 	/*
1412 	 * We don't want to refresh inode->i_size,
1413 	 * because we may have cached data
1414 	 */
1415 	flags = (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) ?
1416 		V9FS_STAT2INODE_KEEP_ISIZE : 0;
1417 	v9fs_stat2inode(st, inode, inode->i_sb, flags);
1418 out:
1419 	p9stat_free(st);
1420 	kfree(st);
1421 	return 0;
1422 }
1423 
1424 static const struct inode_operations v9fs_dir_inode_operations_dotu = {
1425 	.create = v9fs_vfs_create,
1426 	.lookup = v9fs_vfs_lookup,
1427 	.atomic_open = v9fs_vfs_atomic_open,
1428 	.symlink = v9fs_vfs_symlink,
1429 	.link = v9fs_vfs_link,
1430 	.unlink = v9fs_vfs_unlink,
1431 	.mkdir = v9fs_vfs_mkdir,
1432 	.rmdir = v9fs_vfs_rmdir,
1433 	.mknod = v9fs_vfs_mknod,
1434 	.rename = v9fs_vfs_rename,
1435 	.getattr = v9fs_vfs_getattr,
1436 	.setattr = v9fs_vfs_setattr,
1437 };
1438 
1439 static const struct inode_operations v9fs_dir_inode_operations = {
1440 	.create = v9fs_vfs_create,
1441 	.lookup = v9fs_vfs_lookup,
1442 	.atomic_open = v9fs_vfs_atomic_open,
1443 	.unlink = v9fs_vfs_unlink,
1444 	.mkdir = v9fs_vfs_mkdir,
1445 	.rmdir = v9fs_vfs_rmdir,
1446 	.mknod = v9fs_vfs_mknod,
1447 	.rename = v9fs_vfs_rename,
1448 	.getattr = v9fs_vfs_getattr,
1449 	.setattr = v9fs_vfs_setattr,
1450 };
1451 
1452 static const struct inode_operations v9fs_file_inode_operations = {
1453 	.getattr = v9fs_vfs_getattr,
1454 	.setattr = v9fs_vfs_setattr,
1455 };
1456 
1457 static const struct inode_operations v9fs_symlink_inode_operations = {
1458 	.get_link = v9fs_vfs_get_link,
1459 	.getattr = v9fs_vfs_getattr,
1460 	.setattr = v9fs_vfs_setattr,
1461 };
1462 
1463