xref: /openbmc/linux/fs/9p/vfs_inode.c (revision 2d4103ae)
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/sched.h>
21 #include <linux/slab.h>
22 #include <linux/xattr.h>
23 #include <linux/posix_acl.h>
24 #include <net/9p/9p.h>
25 #include <net/9p/client.h>
26 
27 #include "v9fs.h"
28 #include "v9fs_vfs.h"
29 #include "fid.h"
30 #include "cache.h"
31 #include "xattr.h"
32 #include "acl.h"
33 
34 static const struct inode_operations v9fs_dir_inode_operations;
35 static const struct inode_operations v9fs_dir_inode_operations_dotu;
36 static const struct inode_operations v9fs_file_inode_operations;
37 static const struct inode_operations v9fs_symlink_inode_operations;
38 
39 /**
40  * unixmode2p9mode - convert unix mode bits to plan 9
41  * @v9ses: v9fs session information
42  * @mode: mode to convert
43  *
44  */
45 
46 static u32 unixmode2p9mode(struct v9fs_session_info *v9ses, umode_t mode)
47 {
48 	int res;
49 
50 	res = mode & 0777;
51 	if (S_ISDIR(mode))
52 		res |= P9_DMDIR;
53 	if (v9fs_proto_dotu(v9ses)) {
54 		if (v9ses->nodev == 0) {
55 			if (S_ISSOCK(mode))
56 				res |= P9_DMSOCKET;
57 			if (S_ISFIFO(mode))
58 				res |= P9_DMNAMEDPIPE;
59 			if (S_ISBLK(mode))
60 				res |= P9_DMDEVICE;
61 			if (S_ISCHR(mode))
62 				res |= P9_DMDEVICE;
63 		}
64 
65 		if ((mode & S_ISUID) == S_ISUID)
66 			res |= P9_DMSETUID;
67 		if ((mode & S_ISGID) == S_ISGID)
68 			res |= P9_DMSETGID;
69 		if ((mode & S_ISVTX) == S_ISVTX)
70 			res |= P9_DMSETVTX;
71 	}
72 	return res;
73 }
74 
75 /**
76  * p9mode2perm- convert plan9 mode bits to unix permission bits
77  * @v9ses: v9fs session information
78  * @stat: p9_wstat from which mode need to be derived
79  *
80  */
81 static int p9mode2perm(struct v9fs_session_info *v9ses,
82 		       struct p9_wstat *stat)
83 {
84 	int res;
85 	int mode = stat->mode;
86 
87 	res = mode & S_IALLUGO;
88 	if (v9fs_proto_dotu(v9ses)) {
89 		if ((mode & P9_DMSETUID) == P9_DMSETUID)
90 			res |= S_ISUID;
91 
92 		if ((mode & P9_DMSETGID) == P9_DMSETGID)
93 			res |= S_ISGID;
94 
95 		if ((mode & P9_DMSETVTX) == P9_DMSETVTX)
96 			res |= S_ISVTX;
97 	}
98 	return res;
99 }
100 
101 /**
102  * p9mode2unixmode- convert plan9 mode bits to unix mode bits
103  * @v9ses: v9fs session information
104  * @stat: p9_wstat from which mode need to be derived
105  * @rdev: major number, minor number in case of device files.
106  *
107  */
108 static umode_t p9mode2unixmode(struct v9fs_session_info *v9ses,
109 			       struct p9_wstat *stat, dev_t *rdev)
110 {
111 	int res, r;
112 	u32 mode = stat->mode;
113 
114 	*rdev = 0;
115 	res = p9mode2perm(v9ses, stat);
116 
117 	if ((mode & P9_DMDIR) == P9_DMDIR)
118 		res |= S_IFDIR;
119 	else if ((mode & P9_DMSYMLINK) && (v9fs_proto_dotu(v9ses)))
120 		res |= S_IFLNK;
121 	else if ((mode & P9_DMSOCKET) && (v9fs_proto_dotu(v9ses))
122 		 && (v9ses->nodev == 0))
123 		res |= S_IFSOCK;
124 	else if ((mode & P9_DMNAMEDPIPE) && (v9fs_proto_dotu(v9ses))
125 		 && (v9ses->nodev == 0))
126 		res |= S_IFIFO;
127 	else if ((mode & P9_DMDEVICE) && (v9fs_proto_dotu(v9ses))
128 		 && (v9ses->nodev == 0)) {
129 		char type = 0;
130 		int major = -1, minor = -1;
131 
132 		r = sscanf(stat->extension, "%c %i %i", &type, &major, &minor);
133 		if (r != 3) {
134 			p9_debug(P9_DEBUG_ERROR,
135 				 "invalid device string, umode will be bogus: %s\n",
136 				 stat->extension);
137 			return res;
138 		}
139 		switch (type) {
140 		case 'c':
141 			res |= S_IFCHR;
142 			break;
143 		case 'b':
144 			res |= S_IFBLK;
145 			break;
146 		default:
147 			p9_debug(P9_DEBUG_ERROR, "Unknown special type %c %s\n",
148 				 type, stat->extension);
149 		}
150 		*rdev = MKDEV(major, minor);
151 	} else
152 		res |= S_IFREG;
153 
154 	return res;
155 }
156 
157 /**
158  * v9fs_uflags2omode- convert posix open flags to plan 9 mode bits
159  * @uflags: flags to convert
160  * @extended: if .u extensions are active
161  */
162 
163 int v9fs_uflags2omode(int uflags, int extended)
164 {
165 	int ret;
166 
167 	ret = 0;
168 	switch (uflags&3) {
169 	default:
170 	case O_RDONLY:
171 		ret = P9_OREAD;
172 		break;
173 
174 	case O_WRONLY:
175 		ret = P9_OWRITE;
176 		break;
177 
178 	case O_RDWR:
179 		ret = P9_ORDWR;
180 		break;
181 	}
182 
183 	if (extended) {
184 		if (uflags & O_EXCL)
185 			ret |= P9_OEXCL;
186 
187 		if (uflags & O_APPEND)
188 			ret |= P9_OAPPEND;
189 	}
190 
191 	return ret;
192 }
193 
194 /**
195  * v9fs_blank_wstat - helper function to setup a 9P stat structure
196  * @wstat: structure to initialize
197  *
198  */
199 
200 void
201 v9fs_blank_wstat(struct p9_wstat *wstat)
202 {
203 	wstat->type = ~0;
204 	wstat->dev = ~0;
205 	wstat->qid.type = ~0;
206 	wstat->qid.version = ~0;
207 	*((long long *)&wstat->qid.path) = ~0;
208 	wstat->mode = ~0;
209 	wstat->atime = ~0;
210 	wstat->mtime = ~0;
211 	wstat->length = ~0;
212 	wstat->name = NULL;
213 	wstat->uid = NULL;
214 	wstat->gid = NULL;
215 	wstat->muid = NULL;
216 	wstat->n_uid = INVALID_UID;
217 	wstat->n_gid = INVALID_GID;
218 	wstat->n_muid = INVALID_UID;
219 	wstat->extension = NULL;
220 }
221 
222 /**
223  * v9fs_alloc_inode - helper function to allocate an inode
224  * @sb: The superblock to allocate the inode from
225  */
226 struct inode *v9fs_alloc_inode(struct super_block *sb)
227 {
228 	struct v9fs_inode *v9inode;
229 
230 	v9inode = alloc_inode_sb(sb, v9fs_inode_cache, GFP_KERNEL);
231 	if (!v9inode)
232 		return NULL;
233 	v9inode->writeback_fid = NULL;
234 	v9inode->cache_validity = 0;
235 	mutex_init(&v9inode->v_mutex);
236 	return &v9inode->netfs.inode;
237 }
238 
239 /**
240  * v9fs_free_inode - destroy an inode
241  * @inode: The inode to be freed
242  */
243 
244 void v9fs_free_inode(struct inode *inode)
245 {
246 	kmem_cache_free(v9fs_inode_cache, V9FS_I(inode));
247 }
248 
249 /*
250  * Set parameters for the netfs library
251  */
252 static void v9fs_set_netfs_context(struct inode *inode)
253 {
254 	struct v9fs_inode *v9inode = V9FS_I(inode);
255 	netfs_inode_init(&v9inode->netfs, &v9fs_req_ops);
256 }
257 
258 int v9fs_init_inode(struct v9fs_session_info *v9ses,
259 		    struct inode *inode, umode_t mode, dev_t rdev)
260 {
261 	int err = 0;
262 
263 	inode_init_owner(&init_user_ns, inode, NULL, mode);
264 	inode->i_blocks = 0;
265 	inode->i_rdev = rdev;
266 	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
267 	inode->i_mapping->a_ops = &v9fs_addr_operations;
268 	inode->i_private = NULL;
269 
270 	switch (mode & S_IFMT) {
271 	case S_IFIFO:
272 	case S_IFBLK:
273 	case S_IFCHR:
274 	case S_IFSOCK:
275 		if (v9fs_proto_dotl(v9ses)) {
276 			inode->i_op = &v9fs_file_inode_operations_dotl;
277 		} else if (v9fs_proto_dotu(v9ses)) {
278 			inode->i_op = &v9fs_file_inode_operations;
279 		} else {
280 			p9_debug(P9_DEBUG_ERROR,
281 				 "special files without extended mode\n");
282 			err = -EINVAL;
283 			goto error;
284 		}
285 		init_special_inode(inode, inode->i_mode, inode->i_rdev);
286 		break;
287 	case S_IFREG:
288 		if (v9fs_proto_dotl(v9ses)) {
289 			inode->i_op = &v9fs_file_inode_operations_dotl;
290 			if (v9ses->cache == CACHE_LOOSE ||
291 			    v9ses->cache == CACHE_FSCACHE)
292 				inode->i_fop =
293 					&v9fs_cached_file_operations_dotl;
294 			else if (v9ses->cache == CACHE_MMAP)
295 				inode->i_fop = &v9fs_mmap_file_operations_dotl;
296 			else
297 				inode->i_fop = &v9fs_file_operations_dotl;
298 		} else {
299 			inode->i_op = &v9fs_file_inode_operations;
300 			if (v9ses->cache == CACHE_LOOSE ||
301 			    v9ses->cache == CACHE_FSCACHE)
302 				inode->i_fop =
303 					&v9fs_cached_file_operations;
304 			else if (v9ses->cache == CACHE_MMAP)
305 				inode->i_fop = &v9fs_mmap_file_operations;
306 			else
307 				inode->i_fop = &v9fs_file_operations;
308 		}
309 
310 		break;
311 	case S_IFLNK:
312 		if (!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)) {
313 			p9_debug(P9_DEBUG_ERROR,
314 				 "extended modes used with legacy protocol\n");
315 			err = -EINVAL;
316 			goto error;
317 		}
318 
319 		if (v9fs_proto_dotl(v9ses))
320 			inode->i_op = &v9fs_symlink_inode_operations_dotl;
321 		else
322 			inode->i_op = &v9fs_symlink_inode_operations;
323 
324 		break;
325 	case S_IFDIR:
326 		inc_nlink(inode);
327 		if (v9fs_proto_dotl(v9ses))
328 			inode->i_op = &v9fs_dir_inode_operations_dotl;
329 		else if (v9fs_proto_dotu(v9ses))
330 			inode->i_op = &v9fs_dir_inode_operations_dotu;
331 		else
332 			inode->i_op = &v9fs_dir_inode_operations;
333 
334 		if (v9fs_proto_dotl(v9ses))
335 			inode->i_fop = &v9fs_dir_operations_dotl;
336 		else
337 			inode->i_fop = &v9fs_dir_operations;
338 
339 		break;
340 	default:
341 		p9_debug(P9_DEBUG_ERROR, "BAD mode 0x%hx S_IFMT 0x%x\n",
342 			 mode, mode & S_IFMT);
343 		err = -EINVAL;
344 		goto error;
345 	}
346 
347 	v9fs_set_netfs_context(inode);
348 error:
349 	return err;
350 
351 }
352 
353 /**
354  * v9fs_get_inode - helper function to setup an inode
355  * @sb: superblock
356  * @mode: mode to setup inode with
357  * @rdev: The device numbers to set
358  */
359 
360 struct inode *v9fs_get_inode(struct super_block *sb, umode_t mode, dev_t rdev)
361 {
362 	int err;
363 	struct inode *inode;
364 	struct v9fs_session_info *v9ses = sb->s_fs_info;
365 
366 	p9_debug(P9_DEBUG_VFS, "super block: %p mode: %ho\n", sb, mode);
367 
368 	inode = new_inode(sb);
369 	if (!inode) {
370 		pr_warn("%s (%d): Problem allocating inode\n",
371 			__func__, task_pid_nr(current));
372 		return ERR_PTR(-ENOMEM);
373 	}
374 	err = v9fs_init_inode(v9ses, inode, mode, rdev);
375 	if (err) {
376 		iput(inode);
377 		return ERR_PTR(err);
378 	}
379 	return inode;
380 }
381 
382 /**
383  * v9fs_evict_inode - Remove an inode from the inode cache
384  * @inode: inode to release
385  *
386  */
387 void v9fs_evict_inode(struct inode *inode)
388 {
389 	struct v9fs_inode *v9inode = V9FS_I(inode);
390 	__le32 version;
391 
392 	truncate_inode_pages_final(&inode->i_data);
393 	version = cpu_to_le32(v9inode->qid.version);
394 	fscache_clear_inode_writeback(v9fs_inode_cookie(v9inode), inode,
395 				      &version);
396 	clear_inode(inode);
397 	filemap_fdatawrite(&inode->i_data);
398 
399 	fscache_relinquish_cookie(v9fs_inode_cookie(v9inode), false);
400 	/* clunk the fid stashed in writeback_fid */
401 	p9_fid_put(v9inode->writeback_fid);
402 	v9inode->writeback_fid = NULL;
403 }
404 
405 static int v9fs_test_inode(struct inode *inode, void *data)
406 {
407 	int umode;
408 	dev_t rdev;
409 	struct v9fs_inode *v9inode = V9FS_I(inode);
410 	struct p9_wstat *st = (struct p9_wstat *)data;
411 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
412 
413 	umode = p9mode2unixmode(v9ses, st, &rdev);
414 	/* don't match inode of different type */
415 	if (inode_wrong_type(inode, umode))
416 		return 0;
417 
418 	/* compare qid details */
419 	if (memcmp(&v9inode->qid.version,
420 		   &st->qid.version, sizeof(v9inode->qid.version)))
421 		return 0;
422 
423 	if (v9inode->qid.type != st->qid.type)
424 		return 0;
425 
426 	if (v9inode->qid.path != st->qid.path)
427 		return 0;
428 	return 1;
429 }
430 
431 static int v9fs_test_new_inode(struct inode *inode, void *data)
432 {
433 	return 0;
434 }
435 
436 static int v9fs_set_inode(struct inode *inode,  void *data)
437 {
438 	struct v9fs_inode *v9inode = V9FS_I(inode);
439 	struct p9_wstat *st = (struct p9_wstat *)data;
440 
441 	memcpy(&v9inode->qid, &st->qid, sizeof(st->qid));
442 	return 0;
443 }
444 
445 static struct inode *v9fs_qid_iget(struct super_block *sb,
446 				   struct p9_qid *qid,
447 				   struct p9_wstat *st,
448 				   int new)
449 {
450 	dev_t rdev;
451 	int retval;
452 	umode_t umode;
453 	unsigned long i_ino;
454 	struct inode *inode;
455 	struct v9fs_session_info *v9ses = sb->s_fs_info;
456 	int (*test)(struct inode *inode, void *data);
457 
458 	if (new)
459 		test = v9fs_test_new_inode;
460 	else
461 		test = v9fs_test_inode;
462 
463 	i_ino = v9fs_qid2ino(qid);
464 	inode = iget5_locked(sb, i_ino, test, v9fs_set_inode, st);
465 	if (!inode)
466 		return ERR_PTR(-ENOMEM);
467 	if (!(inode->i_state & I_NEW))
468 		return inode;
469 	/*
470 	 * initialize the inode with the stat info
471 	 * FIXME!! we may need support for stale inodes
472 	 * later.
473 	 */
474 	inode->i_ino = i_ino;
475 	umode = p9mode2unixmode(v9ses, st, &rdev);
476 	retval = v9fs_init_inode(v9ses, inode, umode, rdev);
477 	if (retval)
478 		goto error;
479 
480 	v9fs_stat2inode(st, inode, sb, 0);
481 	v9fs_cache_inode_get_cookie(inode);
482 	unlock_new_inode(inode);
483 	return inode;
484 error:
485 	iget_failed(inode);
486 	return ERR_PTR(retval);
487 
488 }
489 
490 struct inode *
491 v9fs_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
492 		    struct super_block *sb, int new)
493 {
494 	struct p9_wstat *st;
495 	struct inode *inode = NULL;
496 
497 	st = p9_client_stat(fid);
498 	if (IS_ERR(st))
499 		return ERR_CAST(st);
500 
501 	inode = v9fs_qid_iget(sb, &st->qid, st, new);
502 	p9stat_free(st);
503 	kfree(st);
504 	return inode;
505 }
506 
507 /**
508  * v9fs_at_to_dotl_flags- convert Linux specific AT flags to
509  * plan 9 AT flag.
510  * @flags: flags to convert
511  */
512 static int v9fs_at_to_dotl_flags(int flags)
513 {
514 	int rflags = 0;
515 
516 	if (flags & AT_REMOVEDIR)
517 		rflags |= P9_DOTL_AT_REMOVEDIR;
518 
519 	return rflags;
520 }
521 
522 /**
523  * v9fs_dec_count - helper functon to drop i_nlink.
524  *
525  * If a directory had nlink <= 2 (including . and ..), then we should not drop
526  * the link count, which indicates the underlying exported fs doesn't maintain
527  * nlink accurately. e.g.
528  * - overlayfs sets nlink to 1 for merged dir
529  * - ext4 (with dir_nlink feature enabled) sets nlink to 1 if a dir has more
530  *   than EXT4_LINK_MAX (65000) links.
531  *
532  * @inode: inode whose nlink is being dropped
533  */
534 static void v9fs_dec_count(struct inode *inode)
535 {
536 	if (!S_ISDIR(inode->i_mode) || inode->i_nlink > 2)
537 		drop_nlink(inode);
538 }
539 
540 /**
541  * v9fs_remove - helper function to remove files and directories
542  * @dir: directory inode that is being deleted
543  * @dentry:  dentry that is being deleted
544  * @flags: removing a directory
545  *
546  */
547 
548 static int v9fs_remove(struct inode *dir, struct dentry *dentry, int flags)
549 {
550 	struct inode *inode;
551 	int retval = -EOPNOTSUPP;
552 	struct p9_fid *v9fid, *dfid;
553 	struct v9fs_session_info *v9ses;
554 
555 	p9_debug(P9_DEBUG_VFS, "inode: %p dentry: %p rmdir: %x\n",
556 		 dir, dentry, flags);
557 
558 	v9ses = v9fs_inode2v9ses(dir);
559 	inode = d_inode(dentry);
560 	dfid = v9fs_parent_fid(dentry);
561 	if (IS_ERR(dfid)) {
562 		retval = PTR_ERR(dfid);
563 		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", retval);
564 		return retval;
565 	}
566 	if (v9fs_proto_dotl(v9ses))
567 		retval = p9_client_unlinkat(dfid, dentry->d_name.name,
568 					    v9fs_at_to_dotl_flags(flags));
569 	p9_fid_put(dfid);
570 	if (retval == -EOPNOTSUPP) {
571 		/* Try the one based on path */
572 		v9fid = v9fs_fid_clone(dentry);
573 		if (IS_ERR(v9fid))
574 			return PTR_ERR(v9fid);
575 		retval = p9_client_remove(v9fid);
576 	}
577 	if (!retval) {
578 		/*
579 		 * directories on unlink should have zero
580 		 * link count
581 		 */
582 		if (flags & AT_REMOVEDIR) {
583 			clear_nlink(inode);
584 			v9fs_dec_count(dir);
585 		} else
586 			v9fs_dec_count(inode);
587 
588 		v9fs_invalidate_inode_attr(inode);
589 		v9fs_invalidate_inode_attr(dir);
590 
591 		/* invalidate all fids associated with dentry */
592 		/* NOTE: This will not include open fids */
593 		dentry->d_op->d_release(dentry);
594 	}
595 	return retval;
596 }
597 
598 /**
599  * v9fs_create - Create a file
600  * @v9ses: session information
601  * @dir: directory that dentry is being created in
602  * @dentry:  dentry that is being created
603  * @extension: 9p2000.u extension string to support devices, etc.
604  * @perm: create permissions
605  * @mode: open mode
606  *
607  */
608 static struct p9_fid *
609 v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
610 		struct dentry *dentry, char *extension, u32 perm, u8 mode)
611 {
612 	int err;
613 	const unsigned char *name;
614 	struct p9_fid *dfid, *ofid = NULL, *fid = NULL;
615 	struct inode *inode;
616 
617 	p9_debug(P9_DEBUG_VFS, "name %pd\n", dentry);
618 
619 	err = 0;
620 	name = dentry->d_name.name;
621 	dfid = v9fs_parent_fid(dentry);
622 	if (IS_ERR(dfid)) {
623 		err = PTR_ERR(dfid);
624 		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", err);
625 		return ERR_PTR(err);
626 	}
627 
628 	/* clone a fid to use for creation */
629 	ofid = clone_fid(dfid);
630 	if (IS_ERR(ofid)) {
631 		err = PTR_ERR(ofid);
632 		p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n", err);
633 		goto error;
634 	}
635 
636 	err = p9_client_fcreate(ofid, name, perm, mode, extension);
637 	if (err < 0) {
638 		p9_debug(P9_DEBUG_VFS, "p9_client_fcreate failed %d\n", err);
639 		goto error;
640 	}
641 
642 	if (!(perm & P9_DMLINK)) {
643 		/* now walk from the parent so we can get unopened fid */
644 		fid = p9_client_walk(dfid, 1, &name, 1);
645 		if (IS_ERR(fid)) {
646 			err = PTR_ERR(fid);
647 			p9_debug(P9_DEBUG_VFS,
648 				   "p9_client_walk failed %d\n", err);
649 			goto error;
650 		}
651 		/*
652 		 * instantiate inode and assign the unopened fid to the dentry
653 		 */
654 		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
655 		if (IS_ERR(inode)) {
656 			err = PTR_ERR(inode);
657 			p9_debug(P9_DEBUG_VFS,
658 				   "inode creation failed %d\n", err);
659 			goto error;
660 		}
661 		v9fs_fid_add(dentry, &fid);
662 		d_instantiate(dentry, inode);
663 	}
664 	p9_fid_put(dfid);
665 	return ofid;
666 error:
667 	p9_fid_put(dfid);
668 	p9_fid_put(ofid);
669 	p9_fid_put(fid);
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_fid_put(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_fid_put(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_fid_put(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_fid_put(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 		goto error;
840 	}
841 
842 	v9fs_invalidate_inode_attr(dir);
843 	inode = d_inode(dentry);
844 	v9inode = V9FS_I(inode);
845 	mutex_lock(&v9inode->v_mutex);
846 	if ((v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) &&
847 	    !v9inode->writeback_fid &&
848 	    ((flags & O_ACCMODE) != O_RDONLY)) {
849 		/*
850 		 * clone a fid and add it to writeback_fid
851 		 * we do it during open time instead of
852 		 * page dirty time via write_begin/page_mkwrite
853 		 * because we want write after unlink usecase
854 		 * to work.
855 		 */
856 		inode_fid = v9fs_writeback_fid(dentry);
857 		if (IS_ERR(inode_fid)) {
858 			err = PTR_ERR(inode_fid);
859 			mutex_unlock(&v9inode->v_mutex);
860 			goto error;
861 		}
862 		v9inode->writeback_fid = (void *) inode_fid;
863 	}
864 	mutex_unlock(&v9inode->v_mutex);
865 	err = finish_open(file, dentry, generic_file_open);
866 	if (err)
867 		goto error;
868 
869 	file->private_data = fid;
870 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
871 		fscache_use_cookie(v9fs_inode_cookie(v9inode),
872 				   file->f_mode & FMODE_WRITE);
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 	p9_fid_put(fid);
882 	goto out;
883 }
884 
885 /**
886  * v9fs_vfs_unlink - VFS unlink hook to delete an inode
887  * @i:  inode that is being unlinked
888  * @d: dentry that is being unlinked
889  *
890  */
891 
892 int v9fs_vfs_unlink(struct inode *i, struct dentry *d)
893 {
894 	return v9fs_remove(i, d, 0);
895 }
896 
897 /**
898  * v9fs_vfs_rmdir - VFS unlink hook to delete a directory
899  * @i:  inode that is being unlinked
900  * @d: dentry that is being unlinked
901  *
902  */
903 
904 int v9fs_vfs_rmdir(struct inode *i, struct dentry *d)
905 {
906 	return v9fs_remove(i, d, AT_REMOVEDIR);
907 }
908 
909 /**
910  * v9fs_vfs_rename - VFS hook to rename an inode
911  * @mnt_userns: The user namespace of the mount
912  * @old_dir:  old dir inode
913  * @old_dentry: old dentry
914  * @new_dir: new dir inode
915  * @new_dentry: new dentry
916  * @flags: RENAME_* flags
917  *
918  */
919 
920 int
921 v9fs_vfs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
922 		struct dentry *old_dentry, struct inode *new_dir,
923 		struct dentry *new_dentry, unsigned int flags)
924 {
925 	int retval;
926 	struct inode *old_inode;
927 	struct inode *new_inode;
928 	struct v9fs_session_info *v9ses;
929 	struct p9_fid *oldfid = NULL, *dfid = NULL;
930 	struct p9_fid *olddirfid = NULL;
931 	struct p9_fid *newdirfid = NULL;
932 	struct p9_wstat wstat;
933 
934 	if (flags)
935 		return -EINVAL;
936 
937 	p9_debug(P9_DEBUG_VFS, "\n");
938 	retval = 0;
939 	old_inode = d_inode(old_dentry);
940 	new_inode = d_inode(new_dentry);
941 	v9ses = v9fs_inode2v9ses(old_inode);
942 	oldfid = v9fs_fid_lookup(old_dentry);
943 	if (IS_ERR(oldfid))
944 		return PTR_ERR(oldfid);
945 
946 	dfid = v9fs_parent_fid(old_dentry);
947 	olddirfid = clone_fid(dfid);
948 	p9_fid_put(dfid);
949 	dfid = NULL;
950 
951 	if (IS_ERR(olddirfid)) {
952 		retval = PTR_ERR(olddirfid);
953 		goto error;
954 	}
955 
956 	dfid = v9fs_parent_fid(new_dentry);
957 	newdirfid = clone_fid(dfid);
958 	p9_fid_put(dfid);
959 	dfid = NULL;
960 
961 	if (IS_ERR(newdirfid)) {
962 		retval = PTR_ERR(newdirfid);
963 		goto error;
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 error_locked;
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 error_locked;
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 error_locked:
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 
1012 error:
1013 	p9_fid_put(newdirfid);
1014 	p9_fid_put(olddirfid);
1015 	p9_fid_put(oldfid);
1016 	return retval;
1017 }
1018 
1019 /**
1020  * v9fs_vfs_getattr - retrieve file metadata
1021  * @mnt_userns: The user namespace of the mount
1022  * @path: Object to query
1023  * @stat: metadata structure to populate
1024  * @request_mask: Mask of STATX_xxx flags indicating the caller's interests
1025  * @flags: AT_STATX_xxx setting
1026  *
1027  */
1028 
1029 static int
1030 v9fs_vfs_getattr(struct user_namespace *mnt_userns, const struct path *path,
1031 		 struct kstat *stat, u32 request_mask, unsigned int flags)
1032 {
1033 	struct dentry *dentry = path->dentry;
1034 	struct v9fs_session_info *v9ses;
1035 	struct p9_fid *fid;
1036 	struct p9_wstat *st;
1037 
1038 	p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
1039 	v9ses = v9fs_dentry2v9ses(dentry);
1040 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
1041 		generic_fillattr(&init_user_ns, d_inode(dentry), stat);
1042 		return 0;
1043 	}
1044 	fid = v9fs_fid_lookup(dentry);
1045 	if (IS_ERR(fid))
1046 		return PTR_ERR(fid);
1047 
1048 	st = p9_client_stat(fid);
1049 	p9_fid_put(fid);
1050 	if (IS_ERR(st))
1051 		return PTR_ERR(st);
1052 
1053 	v9fs_stat2inode(st, d_inode(dentry), dentry->d_sb, 0);
1054 	generic_fillattr(&init_user_ns, d_inode(dentry), stat);
1055 
1056 	p9stat_free(st);
1057 	kfree(st);
1058 	return 0;
1059 }
1060 
1061 /**
1062  * v9fs_vfs_setattr - set file metadata
1063  * @mnt_userns: The user namespace of the mount
1064  * @dentry: file whose metadata to set
1065  * @iattr: metadata assignment structure
1066  *
1067  */
1068 
1069 static int v9fs_vfs_setattr(struct user_namespace *mnt_userns,
1070 			    struct dentry *dentry, struct iattr *iattr)
1071 {
1072 	int retval, use_dentry = 0;
1073 	struct inode *inode = d_inode(dentry);
1074 	struct v9fs_inode *v9inode = V9FS_I(inode);
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(inode->i_mapping);
1121 
1122 	retval = p9_client_wstat(fid, &wstat);
1123 
1124 	if (use_dentry)
1125 		p9_fid_put(fid);
1126 
1127 	if (retval < 0)
1128 		return retval;
1129 
1130 	if ((iattr->ia_valid & ATTR_SIZE) &&
1131 	    iattr->ia_size != i_size_read(inode)) {
1132 		truncate_setsize(inode, iattr->ia_size);
1133 		fscache_resize_cookie(v9fs_inode_cookie(v9inode), iattr->ia_size);
1134 	}
1135 
1136 	v9fs_invalidate_inode_attr(inode);
1137 
1138 	setattr_copy(&init_user_ns, inode, iattr);
1139 	mark_inode_dirty(inode);
1140 	return 0;
1141 }
1142 
1143 /**
1144  * v9fs_stat2inode - populate an inode structure with mistat info
1145  * @stat: Plan 9 metadata (mistat) structure
1146  * @inode: inode to populate
1147  * @sb: superblock of filesystem
1148  * @flags: control flags (e.g. V9FS_STAT2INODE_KEEP_ISIZE)
1149  *
1150  */
1151 
1152 void
1153 v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
1154 		 struct super_block *sb, unsigned int flags)
1155 {
1156 	umode_t mode;
1157 	struct v9fs_session_info *v9ses = sb->s_fs_info;
1158 	struct v9fs_inode *v9inode = V9FS_I(inode);
1159 
1160 	set_nlink(inode, 1);
1161 
1162 	inode->i_atime.tv_sec = stat->atime;
1163 	inode->i_mtime.tv_sec = stat->mtime;
1164 	inode->i_ctime.tv_sec = stat->mtime;
1165 
1166 	inode->i_uid = v9ses->dfltuid;
1167 	inode->i_gid = v9ses->dfltgid;
1168 
1169 	if (v9fs_proto_dotu(v9ses)) {
1170 		inode->i_uid = stat->n_uid;
1171 		inode->i_gid = stat->n_gid;
1172 	}
1173 	if ((S_ISREG(inode->i_mode)) || (S_ISDIR(inode->i_mode))) {
1174 		if (v9fs_proto_dotu(v9ses)) {
1175 			unsigned int i_nlink;
1176 			/*
1177 			 * Hadlink support got added later to the .u extension.
1178 			 * So there can be a server out there that doesn't
1179 			 * support this even with .u extension. That would
1180 			 * just leave us with stat->extension being an empty
1181 			 * string, though.
1182 			 */
1183 			/* HARDLINKCOUNT %u */
1184 			if (sscanf(stat->extension,
1185 				   " HARDLINKCOUNT %u", &i_nlink) == 1)
1186 				set_nlink(inode, i_nlink);
1187 		}
1188 	}
1189 	mode = p9mode2perm(v9ses, stat);
1190 	mode |= inode->i_mode & ~S_IALLUGO;
1191 	inode->i_mode = mode;
1192 
1193 	if (!(flags & V9FS_STAT2INODE_KEEP_ISIZE))
1194 		v9fs_i_size_write(inode, stat->length);
1195 	/* not real number of blocks, but 512 byte ones ... */
1196 	inode->i_blocks = (stat->length + 512 - 1) >> 9;
1197 	v9inode->cache_validity &= ~V9FS_INO_INVALID_ATTR;
1198 }
1199 
1200 /**
1201  * v9fs_qid2ino - convert qid into inode number
1202  * @qid: qid to hash
1203  *
1204  * BUG: potential for inode number collisions?
1205  */
1206 
1207 ino_t v9fs_qid2ino(struct p9_qid *qid)
1208 {
1209 	u64 path = qid->path + 2;
1210 	ino_t i = 0;
1211 
1212 	if (sizeof(ino_t) == sizeof(path))
1213 		memcpy(&i, &path, sizeof(ino_t));
1214 	else
1215 		i = (ino_t) (path ^ (path >> 32));
1216 
1217 	return i;
1218 }
1219 
1220 /**
1221  * v9fs_vfs_get_link - follow a symlink path
1222  * @dentry: dentry for symlink
1223  * @inode: inode for symlink
1224  * @done: delayed call for when we are done with the return value
1225  */
1226 
1227 static const char *v9fs_vfs_get_link(struct dentry *dentry,
1228 				     struct inode *inode,
1229 				     struct delayed_call *done)
1230 {
1231 	struct v9fs_session_info *v9ses;
1232 	struct p9_fid *fid;
1233 	struct p9_wstat *st;
1234 	char *res;
1235 
1236 	if (!dentry)
1237 		return ERR_PTR(-ECHILD);
1238 
1239 	v9ses = v9fs_dentry2v9ses(dentry);
1240 	if (!v9fs_proto_dotu(v9ses))
1241 		return ERR_PTR(-EBADF);
1242 
1243 	p9_debug(P9_DEBUG_VFS, "%pd\n", dentry);
1244 	fid = v9fs_fid_lookup(dentry);
1245 
1246 	if (IS_ERR(fid))
1247 		return ERR_CAST(fid);
1248 
1249 	st = p9_client_stat(fid);
1250 	p9_fid_put(fid);
1251 	if (IS_ERR(st))
1252 		return ERR_CAST(st);
1253 
1254 	if (!(st->mode & P9_DMSYMLINK)) {
1255 		p9stat_free(st);
1256 		kfree(st);
1257 		return ERR_PTR(-EINVAL);
1258 	}
1259 	res = st->extension;
1260 	st->extension = NULL;
1261 	if (strlen(res) >= PATH_MAX)
1262 		res[PATH_MAX - 1] = '\0';
1263 
1264 	p9stat_free(st);
1265 	kfree(st);
1266 	set_delayed_call(done, kfree_link, res);
1267 	return res;
1268 }
1269 
1270 /**
1271  * v9fs_vfs_mkspecial - create a special file
1272  * @dir: inode to create special file in
1273  * @dentry: dentry to create
1274  * @perm: mode to create special file
1275  * @extension: 9p2000.u format extension string representing special file
1276  *
1277  */
1278 
1279 static int v9fs_vfs_mkspecial(struct inode *dir, struct dentry *dentry,
1280 	u32 perm, const char *extension)
1281 {
1282 	struct p9_fid *fid;
1283 	struct v9fs_session_info *v9ses;
1284 
1285 	v9ses = v9fs_inode2v9ses(dir);
1286 	if (!v9fs_proto_dotu(v9ses)) {
1287 		p9_debug(P9_DEBUG_ERROR, "not extended\n");
1288 		return -EPERM;
1289 	}
1290 
1291 	fid = v9fs_create(v9ses, dir, dentry, (char *) extension, perm,
1292 								P9_OREAD);
1293 	if (IS_ERR(fid))
1294 		return PTR_ERR(fid);
1295 
1296 	v9fs_invalidate_inode_attr(dir);
1297 	p9_fid_put(fid);
1298 	return 0;
1299 }
1300 
1301 /**
1302  * v9fs_vfs_symlink - helper function to create symlinks
1303  * @mnt_userns: The user namespace of the mount
1304  * @dir: directory inode containing symlink
1305  * @dentry: dentry for symlink
1306  * @symname: symlink data
1307  *
1308  * See Also: 9P2000.u RFC for more information
1309  *
1310  */
1311 
1312 static int
1313 v9fs_vfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
1314 		 struct dentry *dentry, const char *symname)
1315 {
1316 	p9_debug(P9_DEBUG_VFS, " %lu,%pd,%s\n",
1317 		 dir->i_ino, dentry, symname);
1318 
1319 	return v9fs_vfs_mkspecial(dir, dentry, P9_DMSYMLINK, symname);
1320 }
1321 
1322 #define U32_MAX_DIGITS 10
1323 
1324 /**
1325  * v9fs_vfs_link - create a hardlink
1326  * @old_dentry: dentry for file to link to
1327  * @dir: inode destination for new link
1328  * @dentry: dentry for link
1329  *
1330  */
1331 
1332 static int
1333 v9fs_vfs_link(struct dentry *old_dentry, struct inode *dir,
1334 	      struct dentry *dentry)
1335 {
1336 	int retval;
1337 	char name[1 + U32_MAX_DIGITS + 2]; /* sign + number + \n + \0 */
1338 	struct p9_fid *oldfid;
1339 
1340 	p9_debug(P9_DEBUG_VFS, " %lu,%pd,%pd\n",
1341 		 dir->i_ino, dentry, old_dentry);
1342 
1343 	oldfid = v9fs_fid_clone(old_dentry);
1344 	if (IS_ERR(oldfid))
1345 		return PTR_ERR(oldfid);
1346 
1347 	sprintf(name, "%d\n", oldfid->fid);
1348 	retval = v9fs_vfs_mkspecial(dir, dentry, P9_DMLINK, name);
1349 	if (!retval) {
1350 		v9fs_refresh_inode(oldfid, d_inode(old_dentry));
1351 		v9fs_invalidate_inode_attr(dir);
1352 	}
1353 	p9_fid_put(oldfid);
1354 	return retval;
1355 }
1356 
1357 /**
1358  * v9fs_vfs_mknod - create a special file
1359  * @mnt_userns: The user namespace of the mount
1360  * @dir: inode destination for new link
1361  * @dentry: dentry for file
1362  * @mode: mode for creation
1363  * @rdev: device associated with special file
1364  *
1365  */
1366 
1367 static int
1368 v9fs_vfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
1369 	       struct dentry *dentry, umode_t mode, dev_t rdev)
1370 {
1371 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
1372 	int retval;
1373 	char name[2 + U32_MAX_DIGITS + 1 + U32_MAX_DIGITS + 1];
1374 	u32 perm;
1375 
1376 	p9_debug(P9_DEBUG_VFS, " %lu,%pd mode: %x MAJOR: %u MINOR: %u\n",
1377 		 dir->i_ino, dentry, mode,
1378 		 MAJOR(rdev), MINOR(rdev));
1379 
1380 	/* build extension */
1381 	if (S_ISBLK(mode))
1382 		sprintf(name, "b %u %u", MAJOR(rdev), MINOR(rdev));
1383 	else if (S_ISCHR(mode))
1384 		sprintf(name, "c %u %u", MAJOR(rdev), MINOR(rdev));
1385 	else
1386 		*name = 0;
1387 
1388 	perm = unixmode2p9mode(v9ses, mode);
1389 	retval = v9fs_vfs_mkspecial(dir, dentry, perm, name);
1390 
1391 	return retval;
1392 }
1393 
1394 int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode)
1395 {
1396 	int umode;
1397 	dev_t rdev;
1398 	struct p9_wstat *st;
1399 	struct v9fs_session_info *v9ses;
1400 	unsigned int flags;
1401 
1402 	v9ses = v9fs_inode2v9ses(inode);
1403 	st = p9_client_stat(fid);
1404 	if (IS_ERR(st))
1405 		return PTR_ERR(st);
1406 	/*
1407 	 * Don't update inode if the file type is different
1408 	 */
1409 	umode = p9mode2unixmode(v9ses, st, &rdev);
1410 	if (inode_wrong_type(inode, umode))
1411 		goto out;
1412 
1413 	/*
1414 	 * We don't want to refresh inode->i_size,
1415 	 * because we may have cached data
1416 	 */
1417 	flags = (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) ?
1418 		V9FS_STAT2INODE_KEEP_ISIZE : 0;
1419 	v9fs_stat2inode(st, inode, inode->i_sb, flags);
1420 out:
1421 	p9stat_free(st);
1422 	kfree(st);
1423 	return 0;
1424 }
1425 
1426 static const struct inode_operations v9fs_dir_inode_operations_dotu = {
1427 	.create = v9fs_vfs_create,
1428 	.lookup = v9fs_vfs_lookup,
1429 	.atomic_open = v9fs_vfs_atomic_open,
1430 	.symlink = v9fs_vfs_symlink,
1431 	.link = v9fs_vfs_link,
1432 	.unlink = v9fs_vfs_unlink,
1433 	.mkdir = v9fs_vfs_mkdir,
1434 	.rmdir = v9fs_vfs_rmdir,
1435 	.mknod = v9fs_vfs_mknod,
1436 	.rename = v9fs_vfs_rename,
1437 	.getattr = v9fs_vfs_getattr,
1438 	.setattr = v9fs_vfs_setattr,
1439 };
1440 
1441 static const struct inode_operations v9fs_dir_inode_operations = {
1442 	.create = v9fs_vfs_create,
1443 	.lookup = v9fs_vfs_lookup,
1444 	.atomic_open = v9fs_vfs_atomic_open,
1445 	.unlink = v9fs_vfs_unlink,
1446 	.mkdir = v9fs_vfs_mkdir,
1447 	.rmdir = v9fs_vfs_rmdir,
1448 	.mknod = v9fs_vfs_mknod,
1449 	.rename = v9fs_vfs_rename,
1450 	.getattr = v9fs_vfs_getattr,
1451 	.setattr = v9fs_vfs_setattr,
1452 };
1453 
1454 static const struct inode_operations v9fs_file_inode_operations = {
1455 	.getattr = v9fs_vfs_getattr,
1456 	.setattr = v9fs_vfs_setattr,
1457 };
1458 
1459 static const struct inode_operations v9fs_symlink_inode_operations = {
1460 	.get_link = v9fs_vfs_get_link,
1461 	.getattr = v9fs_vfs_getattr,
1462 	.setattr = v9fs_vfs_setattr,
1463 };
1464 
1465