xref: /openbmc/linux/fs/9p/vfs_inode.c (revision ae213c44)
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 	mutex_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_free_inode - destroy an inode
257  *
258  */
259 
260 void v9fs_free_inode(struct inode *inode)
261 {
262 	kmem_cache_free(v9fs_inode_cache, V9FS_I(inode));
263 }
264 
265 int v9fs_init_inode(struct v9fs_session_info *v9ses,
266 		    struct inode *inode, umode_t mode, dev_t rdev)
267 {
268 	int err = 0;
269 
270 	inode_init_owner(inode, NULL, mode);
271 	inode->i_blocks = 0;
272 	inode->i_rdev = rdev;
273 	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
274 	inode->i_mapping->a_ops = &v9fs_addr_operations;
275 
276 	switch (mode & S_IFMT) {
277 	case S_IFIFO:
278 	case S_IFBLK:
279 	case S_IFCHR:
280 	case S_IFSOCK:
281 		if (v9fs_proto_dotl(v9ses)) {
282 			inode->i_op = &v9fs_file_inode_operations_dotl;
283 		} else if (v9fs_proto_dotu(v9ses)) {
284 			inode->i_op = &v9fs_file_inode_operations;
285 		} else {
286 			p9_debug(P9_DEBUG_ERROR,
287 				 "special files without extended mode\n");
288 			err = -EINVAL;
289 			goto error;
290 		}
291 		init_special_inode(inode, inode->i_mode, inode->i_rdev);
292 		break;
293 	case S_IFREG:
294 		if (v9fs_proto_dotl(v9ses)) {
295 			inode->i_op = &v9fs_file_inode_operations_dotl;
296 			if (v9ses->cache == CACHE_LOOSE ||
297 			    v9ses->cache == CACHE_FSCACHE)
298 				inode->i_fop =
299 					&v9fs_cached_file_operations_dotl;
300 			else if (v9ses->cache == CACHE_MMAP)
301 				inode->i_fop = &v9fs_mmap_file_operations_dotl;
302 			else
303 				inode->i_fop = &v9fs_file_operations_dotl;
304 		} else {
305 			inode->i_op = &v9fs_file_inode_operations;
306 			if (v9ses->cache == CACHE_LOOSE ||
307 			    v9ses->cache == CACHE_FSCACHE)
308 				inode->i_fop =
309 					&v9fs_cached_file_operations;
310 			else if (v9ses->cache == CACHE_MMAP)
311 				inode->i_fop = &v9fs_mmap_file_operations;
312 			else
313 				inode->i_fop = &v9fs_file_operations;
314 		}
315 
316 		break;
317 	case S_IFLNK:
318 		if (!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)) {
319 			p9_debug(P9_DEBUG_ERROR,
320 				 "extended modes used with legacy protocol\n");
321 			err = -EINVAL;
322 			goto error;
323 		}
324 
325 		if (v9fs_proto_dotl(v9ses))
326 			inode->i_op = &v9fs_symlink_inode_operations_dotl;
327 		else
328 			inode->i_op = &v9fs_symlink_inode_operations;
329 
330 		break;
331 	case S_IFDIR:
332 		inc_nlink(inode);
333 		if (v9fs_proto_dotl(v9ses))
334 			inode->i_op = &v9fs_dir_inode_operations_dotl;
335 		else if (v9fs_proto_dotu(v9ses))
336 			inode->i_op = &v9fs_dir_inode_operations_dotu;
337 		else
338 			inode->i_op = &v9fs_dir_inode_operations;
339 
340 		if (v9fs_proto_dotl(v9ses))
341 			inode->i_fop = &v9fs_dir_operations_dotl;
342 		else
343 			inode->i_fop = &v9fs_dir_operations;
344 
345 		break;
346 	default:
347 		p9_debug(P9_DEBUG_ERROR, "BAD mode 0x%hx S_IFMT 0x%x\n",
348 			 mode, mode & S_IFMT);
349 		err = -EINVAL;
350 		goto error;
351 	}
352 error:
353 	return err;
354 
355 }
356 
357 /**
358  * v9fs_get_inode - helper function to setup an inode
359  * @sb: superblock
360  * @mode: mode to setup inode with
361  *
362  */
363 
364 struct inode *v9fs_get_inode(struct super_block *sb, umode_t mode, dev_t rdev)
365 {
366 	int err;
367 	struct inode *inode;
368 	struct v9fs_session_info *v9ses = sb->s_fs_info;
369 
370 	p9_debug(P9_DEBUG_VFS, "super block: %p mode: %ho\n", sb, mode);
371 
372 	inode = new_inode(sb);
373 	if (!inode) {
374 		pr_warn("%s (%d): Problem allocating inode\n",
375 			__func__, task_pid_nr(current));
376 		return ERR_PTR(-ENOMEM);
377 	}
378 	err = v9fs_init_inode(v9ses, inode, mode, rdev);
379 	if (err) {
380 		iput(inode);
381 		return ERR_PTR(err);
382 	}
383 	return inode;
384 }
385 
386 /*
387 static struct v9fs_fid*
388 v9fs_clone_walk(struct v9fs_session_info *v9ses, u32 fid, struct dentry *dentry)
389 {
390 	int err;
391 	int nfid;
392 	struct v9fs_fid *ret;
393 	struct v9fs_fcall *fcall;
394 
395 	nfid = v9fs_get_idpool(&v9ses->fidpool);
396 	if (nfid < 0) {
397 		eprintk(KERN_WARNING, "no free fids available\n");
398 		return ERR_PTR(-ENOSPC);
399 	}
400 
401 	err = v9fs_t_walk(v9ses, fid, nfid, (char *) dentry->d_name.name,
402 		&fcall);
403 
404 	if (err < 0) {
405 		if (fcall && fcall->id == RWALK)
406 			goto clunk_fid;
407 
408 		PRINT_FCALL_ERROR("walk error", fcall);
409 		v9fs_put_idpool(nfid, &v9ses->fidpool);
410 		goto error;
411 	}
412 
413 	kfree(fcall);
414 	fcall = NULL;
415 	ret = v9fs_fid_create(v9ses, nfid);
416 	if (!ret) {
417 		err = -ENOMEM;
418 		goto clunk_fid;
419 	}
420 
421 	err = v9fs_fid_insert(ret, dentry);
422 	if (err < 0) {
423 		v9fs_fid_destroy(ret);
424 		goto clunk_fid;
425 	}
426 
427 	return ret;
428 
429 clunk_fid:
430 	v9fs_t_clunk(v9ses, nfid);
431 
432 error:
433 	kfree(fcall);
434 	return ERR_PTR(err);
435 }
436 */
437 
438 
439 /**
440  * v9fs_clear_inode - release an inode
441  * @inode: inode to release
442  *
443  */
444 void v9fs_evict_inode(struct inode *inode)
445 {
446 	struct v9fs_inode *v9inode = V9FS_I(inode);
447 
448 	truncate_inode_pages_final(&inode->i_data);
449 	clear_inode(inode);
450 	filemap_fdatawrite(&inode->i_data);
451 
452 	v9fs_cache_inode_put_cookie(inode);
453 	/* clunk the fid stashed in writeback_fid */
454 	if (v9inode->writeback_fid) {
455 		p9_client_clunk(v9inode->writeback_fid);
456 		v9inode->writeback_fid = NULL;
457 	}
458 }
459 
460 static int v9fs_test_inode(struct inode *inode, void *data)
461 {
462 	int umode;
463 	dev_t rdev;
464 	struct v9fs_inode *v9inode = V9FS_I(inode);
465 	struct p9_wstat *st = (struct p9_wstat *)data;
466 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
467 
468 	umode = p9mode2unixmode(v9ses, st, &rdev);
469 	/* don't match inode of different type */
470 	if ((inode->i_mode & S_IFMT) != (umode & S_IFMT))
471 		return 0;
472 
473 	/* compare qid details */
474 	if (memcmp(&v9inode->qid.version,
475 		   &st->qid.version, sizeof(v9inode->qid.version)))
476 		return 0;
477 
478 	if (v9inode->qid.type != st->qid.type)
479 		return 0;
480 
481 	if (v9inode->qid.path != st->qid.path)
482 		return 0;
483 	return 1;
484 }
485 
486 static int v9fs_test_new_inode(struct inode *inode, void *data)
487 {
488 	return 0;
489 }
490 
491 static int v9fs_set_inode(struct inode *inode,  void *data)
492 {
493 	struct v9fs_inode *v9inode = V9FS_I(inode);
494 	struct p9_wstat *st = (struct p9_wstat *)data;
495 
496 	memcpy(&v9inode->qid, &st->qid, sizeof(st->qid));
497 	return 0;
498 }
499 
500 static struct inode *v9fs_qid_iget(struct super_block *sb,
501 				   struct p9_qid *qid,
502 				   struct p9_wstat *st,
503 				   int new)
504 {
505 	dev_t rdev;
506 	int retval;
507 	umode_t umode;
508 	unsigned long i_ino;
509 	struct inode *inode;
510 	struct v9fs_session_info *v9ses = sb->s_fs_info;
511 	int (*test)(struct inode *, void *);
512 
513 	if (new)
514 		test = v9fs_test_new_inode;
515 	else
516 		test = v9fs_test_inode;
517 
518 	i_ino = v9fs_qid2ino(qid);
519 	inode = iget5_locked(sb, i_ino, test, v9fs_set_inode, st);
520 	if (!inode)
521 		return ERR_PTR(-ENOMEM);
522 	if (!(inode->i_state & I_NEW))
523 		return inode;
524 	/*
525 	 * initialize the inode with the stat info
526 	 * FIXME!! we may need support for stale inodes
527 	 * later.
528 	 */
529 	inode->i_ino = i_ino;
530 	umode = p9mode2unixmode(v9ses, st, &rdev);
531 	retval = v9fs_init_inode(v9ses, inode, umode, rdev);
532 	if (retval)
533 		goto error;
534 
535 	v9fs_stat2inode(st, inode, sb, 0);
536 	v9fs_cache_inode_get_cookie(inode);
537 	unlock_new_inode(inode);
538 	return inode;
539 error:
540 	iget_failed(inode);
541 	return ERR_PTR(retval);
542 
543 }
544 
545 struct inode *
546 v9fs_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
547 		    struct super_block *sb, int new)
548 {
549 	struct p9_wstat *st;
550 	struct inode *inode = NULL;
551 
552 	st = p9_client_stat(fid);
553 	if (IS_ERR(st))
554 		return ERR_CAST(st);
555 
556 	inode = v9fs_qid_iget(sb, &st->qid, st, new);
557 	p9stat_free(st);
558 	kfree(st);
559 	return inode;
560 }
561 
562 /**
563  * v9fs_at_to_dotl_flags- convert Linux specific AT flags to
564  * plan 9 AT flag.
565  * @flags: flags to convert
566  */
567 static int v9fs_at_to_dotl_flags(int flags)
568 {
569 	int rflags = 0;
570 	if (flags & AT_REMOVEDIR)
571 		rflags |= P9_DOTL_AT_REMOVEDIR;
572 	return rflags;
573 }
574 
575 /**
576  * v9fs_dec_count - helper functon to drop i_nlink.
577  *
578  * If a directory had nlink <= 2 (including . and ..), then we should not drop
579  * the link count, which indicates the underlying exported fs doesn't maintain
580  * nlink accurately. e.g.
581  * - overlayfs sets nlink to 1 for merged dir
582  * - ext4 (with dir_nlink feature enabled) sets nlink to 1 if a dir has more
583  *   than EXT4_LINK_MAX (65000) links.
584  *
585  * @inode: inode whose nlink is being dropped
586  */
587 static void v9fs_dec_count(struct inode *inode)
588 {
589 	if (!S_ISDIR(inode->i_mode) || inode->i_nlink > 2)
590 		drop_nlink(inode);
591 }
592 
593 /**
594  * v9fs_remove - helper function to remove files and directories
595  * @dir: directory inode that is being deleted
596  * @dentry:  dentry that is being deleted
597  * @flags: removing a directory
598  *
599  */
600 
601 static int v9fs_remove(struct inode *dir, struct dentry *dentry, int flags)
602 {
603 	struct inode *inode;
604 	int retval = -EOPNOTSUPP;
605 	struct p9_fid *v9fid, *dfid;
606 	struct v9fs_session_info *v9ses;
607 
608 	p9_debug(P9_DEBUG_VFS, "inode: %p dentry: %p rmdir: %x\n",
609 		 dir, dentry, flags);
610 
611 	v9ses = v9fs_inode2v9ses(dir);
612 	inode = d_inode(dentry);
613 	dfid = v9fs_parent_fid(dentry);
614 	if (IS_ERR(dfid)) {
615 		retval = PTR_ERR(dfid);
616 		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", retval);
617 		return retval;
618 	}
619 	if (v9fs_proto_dotl(v9ses))
620 		retval = p9_client_unlinkat(dfid, dentry->d_name.name,
621 					    v9fs_at_to_dotl_flags(flags));
622 	if (retval == -EOPNOTSUPP) {
623 		/* Try the one based on path */
624 		v9fid = v9fs_fid_clone(dentry);
625 		if (IS_ERR(v9fid))
626 			return PTR_ERR(v9fid);
627 		retval = p9_client_remove(v9fid);
628 	}
629 	if (!retval) {
630 		/*
631 		 * directories on unlink should have zero
632 		 * link count
633 		 */
634 		if (flags & AT_REMOVEDIR) {
635 			clear_nlink(inode);
636 			v9fs_dec_count(dir);
637 		} else
638 			v9fs_dec_count(inode);
639 
640 		v9fs_invalidate_inode_attr(inode);
641 		v9fs_invalidate_inode_attr(dir);
642 	}
643 	return retval;
644 }
645 
646 /**
647  * v9fs_create - Create a file
648  * @v9ses: session information
649  * @dir: directory that dentry is being created in
650  * @dentry:  dentry that is being created
651  * @extension: 9p2000.u extension string to support devices, etc.
652  * @perm: create permissions
653  * @mode: open mode
654  *
655  */
656 static struct p9_fid *
657 v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
658 		struct dentry *dentry, char *extension, u32 perm, u8 mode)
659 {
660 	int err;
661 	const unsigned char *name;
662 	struct p9_fid *dfid, *ofid, *fid;
663 	struct inode *inode;
664 
665 	p9_debug(P9_DEBUG_VFS, "name %pd\n", dentry);
666 
667 	err = 0;
668 	ofid = NULL;
669 	fid = NULL;
670 	name = dentry->d_name.name;
671 	dfid = v9fs_parent_fid(dentry);
672 	if (IS_ERR(dfid)) {
673 		err = PTR_ERR(dfid);
674 		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", err);
675 		return ERR_PTR(err);
676 	}
677 
678 	/* clone a fid to use for creation */
679 	ofid = clone_fid(dfid);
680 	if (IS_ERR(ofid)) {
681 		err = PTR_ERR(ofid);
682 		p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n", err);
683 		return ERR_PTR(err);
684 	}
685 
686 	err = p9_client_fcreate(ofid, name, perm, mode, extension);
687 	if (err < 0) {
688 		p9_debug(P9_DEBUG_VFS, "p9_client_fcreate failed %d\n", err);
689 		goto error;
690 	}
691 
692 	if (!(perm & P9_DMLINK)) {
693 		/* now walk from the parent so we can get unopened fid */
694 		fid = p9_client_walk(dfid, 1, &name, 1);
695 		if (IS_ERR(fid)) {
696 			err = PTR_ERR(fid);
697 			p9_debug(P9_DEBUG_VFS,
698 				   "p9_client_walk failed %d\n", err);
699 			fid = NULL;
700 			goto error;
701 		}
702 		/*
703 		 * instantiate inode and assign the unopened fid to the dentry
704 		 */
705 		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
706 		if (IS_ERR(inode)) {
707 			err = PTR_ERR(inode);
708 			p9_debug(P9_DEBUG_VFS,
709 				   "inode creation failed %d\n", err);
710 			goto error;
711 		}
712 		v9fs_fid_add(dentry, fid);
713 		d_instantiate(dentry, inode);
714 	}
715 	return ofid;
716 error:
717 	if (ofid)
718 		p9_client_clunk(ofid);
719 
720 	if (fid)
721 		p9_client_clunk(fid);
722 
723 	return ERR_PTR(err);
724 }
725 
726 /**
727  * v9fs_vfs_create - VFS hook to create a regular file
728  *
729  * open(.., O_CREAT) is handled in v9fs_vfs_atomic_open().  This is only called
730  * for mknod(2).
731  *
732  * @dir: directory inode that is being created
733  * @dentry:  dentry that is being deleted
734  * @mode: create permissions
735  *
736  */
737 
738 static int
739 v9fs_vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
740 		bool excl)
741 {
742 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
743 	u32 perm = unixmode2p9mode(v9ses, mode);
744 	struct p9_fid *fid;
745 
746 	/* P9_OEXCL? */
747 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_ORDWR);
748 	if (IS_ERR(fid))
749 		return PTR_ERR(fid);
750 
751 	v9fs_invalidate_inode_attr(dir);
752 	p9_client_clunk(fid);
753 
754 	return 0;
755 }
756 
757 /**
758  * v9fs_vfs_mkdir - VFS mkdir hook to create a directory
759  * @dir:  inode that is being unlinked
760  * @dentry: dentry that is being unlinked
761  * @mode: mode for new directory
762  *
763  */
764 
765 static int v9fs_vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
766 {
767 	int err;
768 	u32 perm;
769 	struct p9_fid *fid;
770 	struct v9fs_session_info *v9ses;
771 
772 	p9_debug(P9_DEBUG_VFS, "name %pd\n", dentry);
773 	err = 0;
774 	v9ses = v9fs_inode2v9ses(dir);
775 	perm = unixmode2p9mode(v9ses, mode | S_IFDIR);
776 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_OREAD);
777 	if (IS_ERR(fid)) {
778 		err = PTR_ERR(fid);
779 		fid = NULL;
780 	} else {
781 		inc_nlink(dir);
782 		v9fs_invalidate_inode_attr(dir);
783 	}
784 
785 	if (fid)
786 		p9_client_clunk(fid);
787 
788 	return err;
789 }
790 
791 /**
792  * v9fs_vfs_lookup - VFS lookup hook to "walk" to a new inode
793  * @dir:  inode that is being walked from
794  * @dentry: dentry that is being walked to?
795  * @flags: lookup flags (unused)
796  *
797  */
798 
799 struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
800 				      unsigned int flags)
801 {
802 	struct dentry *res;
803 	struct v9fs_session_info *v9ses;
804 	struct p9_fid *dfid, *fid;
805 	struct inode *inode;
806 	const unsigned char *name;
807 
808 	p9_debug(P9_DEBUG_VFS, "dir: %p dentry: (%pd) %p flags: %x\n",
809 		 dir, dentry, dentry, flags);
810 
811 	if (dentry->d_name.len > NAME_MAX)
812 		return ERR_PTR(-ENAMETOOLONG);
813 
814 	v9ses = v9fs_inode2v9ses(dir);
815 	/* We can walk d_parent because we hold the dir->i_mutex */
816 	dfid = v9fs_parent_fid(dentry);
817 	if (IS_ERR(dfid))
818 		return ERR_CAST(dfid);
819 
820 	/*
821 	 * Make sure we don't use a wrong inode due to parallel
822 	 * unlink. For cached mode create calls request for new
823 	 * inode. But with cache disabled, lookup should do this.
824 	 */
825 	name = dentry->d_name.name;
826 	fid = p9_client_walk(dfid, 1, &name, 1);
827 	if (fid == ERR_PTR(-ENOENT))
828 		inode = NULL;
829 	else if (IS_ERR(fid))
830 		inode = ERR_CAST(fid);
831 	else if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
832 		inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
833 	else
834 		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
835 	/*
836 	 * If we had a rename on the server and a parallel lookup
837 	 * for the new name, then make sure we instantiate with
838 	 * the new name. ie look up for a/b, while on server somebody
839 	 * moved b under k and client parallely did a lookup for
840 	 * k/b.
841 	 */
842 	res = d_splice_alias(inode, dentry);
843 	if (!IS_ERR(fid)) {
844 		if (!res)
845 			v9fs_fid_add(dentry, fid);
846 		else if (!IS_ERR(res))
847 			v9fs_fid_add(res, fid);
848 		else
849 			p9_client_clunk(fid);
850 	}
851 	return res;
852 }
853 
854 static int
855 v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
856 		     struct file *file, unsigned flags, umode_t mode)
857 {
858 	int err;
859 	u32 perm;
860 	struct v9fs_inode *v9inode;
861 	struct v9fs_session_info *v9ses;
862 	struct p9_fid *fid, *inode_fid;
863 	struct dentry *res = NULL;
864 
865 	if (d_in_lookup(dentry)) {
866 		res = v9fs_vfs_lookup(dir, dentry, 0);
867 		if (IS_ERR(res))
868 			return PTR_ERR(res);
869 
870 		if (res)
871 			dentry = res;
872 	}
873 
874 	/* Only creates */
875 	if (!(flags & O_CREAT) || d_really_is_positive(dentry))
876 		return finish_no_open(file, res);
877 
878 	err = 0;
879 
880 	v9ses = v9fs_inode2v9ses(dir);
881 	perm = unixmode2p9mode(v9ses, mode);
882 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm,
883 				v9fs_uflags2omode(flags,
884 						v9fs_proto_dotu(v9ses)));
885 	if (IS_ERR(fid)) {
886 		err = PTR_ERR(fid);
887 		fid = NULL;
888 		goto error;
889 	}
890 
891 	v9fs_invalidate_inode_attr(dir);
892 	v9inode = V9FS_I(d_inode(dentry));
893 	mutex_lock(&v9inode->v_mutex);
894 	if ((v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) &&
895 	    !v9inode->writeback_fid &&
896 	    ((flags & O_ACCMODE) != O_RDONLY)) {
897 		/*
898 		 * clone a fid and add it to writeback_fid
899 		 * we do it during open time instead of
900 		 * page dirty time via write_begin/page_mkwrite
901 		 * because we want write after unlink usecase
902 		 * to work.
903 		 */
904 		inode_fid = v9fs_writeback_fid(dentry);
905 		if (IS_ERR(inode_fid)) {
906 			err = PTR_ERR(inode_fid);
907 			mutex_unlock(&v9inode->v_mutex);
908 			goto error;
909 		}
910 		v9inode->writeback_fid = (void *) inode_fid;
911 	}
912 	mutex_unlock(&v9inode->v_mutex);
913 	err = finish_open(file, dentry, generic_file_open);
914 	if (err)
915 		goto error;
916 
917 	file->private_data = fid;
918 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
919 		v9fs_cache_inode_set_cookie(d_inode(dentry), file);
920 
921 	file->f_mode |= FMODE_CREATED;
922 out:
923 	dput(res);
924 	return err;
925 
926 error:
927 	if (fid)
928 		p9_client_clunk(fid);
929 	goto out;
930 }
931 
932 /**
933  * v9fs_vfs_unlink - VFS unlink hook to delete an inode
934  * @i:  inode that is being unlinked
935  * @d: dentry that is being unlinked
936  *
937  */
938 
939 int v9fs_vfs_unlink(struct inode *i, struct dentry *d)
940 {
941 	return v9fs_remove(i, d, 0);
942 }
943 
944 /**
945  * v9fs_vfs_rmdir - VFS unlink hook to delete a directory
946  * @i:  inode that is being unlinked
947  * @d: dentry that is being unlinked
948  *
949  */
950 
951 int v9fs_vfs_rmdir(struct inode *i, struct dentry *d)
952 {
953 	return v9fs_remove(i, d, AT_REMOVEDIR);
954 }
955 
956 /**
957  * v9fs_vfs_rename - VFS hook to rename an inode
958  * @old_dir:  old dir inode
959  * @old_dentry: old dentry
960  * @new_dir: new dir inode
961  * @new_dentry: new dentry
962  *
963  */
964 
965 int
966 v9fs_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
967 		struct inode *new_dir, struct dentry *new_dentry,
968 		unsigned int flags)
969 {
970 	int retval;
971 	struct inode *old_inode;
972 	struct inode *new_inode;
973 	struct v9fs_session_info *v9ses;
974 	struct p9_fid *oldfid;
975 	struct p9_fid *olddirfid;
976 	struct p9_fid *newdirfid;
977 	struct p9_wstat wstat;
978 
979 	if (flags)
980 		return -EINVAL;
981 
982 	p9_debug(P9_DEBUG_VFS, "\n");
983 	retval = 0;
984 	old_inode = d_inode(old_dentry);
985 	new_inode = d_inode(new_dentry);
986 	v9ses = v9fs_inode2v9ses(old_inode);
987 	oldfid = v9fs_fid_lookup(old_dentry);
988 	if (IS_ERR(oldfid))
989 		return PTR_ERR(oldfid);
990 
991 	olddirfid = clone_fid(v9fs_parent_fid(old_dentry));
992 	if (IS_ERR(olddirfid)) {
993 		retval = PTR_ERR(olddirfid);
994 		goto done;
995 	}
996 
997 	newdirfid = clone_fid(v9fs_parent_fid(new_dentry));
998 	if (IS_ERR(newdirfid)) {
999 		retval = PTR_ERR(newdirfid);
1000 		goto clunk_olddir;
1001 	}
1002 
1003 	down_write(&v9ses->rename_sem);
1004 	if (v9fs_proto_dotl(v9ses)) {
1005 		retval = p9_client_renameat(olddirfid, old_dentry->d_name.name,
1006 					    newdirfid, new_dentry->d_name.name);
1007 		if (retval == -EOPNOTSUPP)
1008 			retval = p9_client_rename(oldfid, newdirfid,
1009 						  new_dentry->d_name.name);
1010 		if (retval != -EOPNOTSUPP)
1011 			goto clunk_newdir;
1012 	}
1013 	if (old_dentry->d_parent != new_dentry->d_parent) {
1014 		/*
1015 		 * 9P .u can only handle file rename in the same directory
1016 		 */
1017 
1018 		p9_debug(P9_DEBUG_ERROR, "old dir and new dir are different\n");
1019 		retval = -EXDEV;
1020 		goto clunk_newdir;
1021 	}
1022 	v9fs_blank_wstat(&wstat);
1023 	wstat.muid = v9ses->uname;
1024 	wstat.name = new_dentry->d_name.name;
1025 	retval = p9_client_wstat(oldfid, &wstat);
1026 
1027 clunk_newdir:
1028 	if (!retval) {
1029 		if (new_inode) {
1030 			if (S_ISDIR(new_inode->i_mode))
1031 				clear_nlink(new_inode);
1032 			else
1033 				v9fs_dec_count(new_inode);
1034 		}
1035 		if (S_ISDIR(old_inode->i_mode)) {
1036 			if (!new_inode)
1037 				inc_nlink(new_dir);
1038 			v9fs_dec_count(old_dir);
1039 		}
1040 		v9fs_invalidate_inode_attr(old_inode);
1041 		v9fs_invalidate_inode_attr(old_dir);
1042 		v9fs_invalidate_inode_attr(new_dir);
1043 
1044 		/* successful rename */
1045 		d_move(old_dentry, new_dentry);
1046 	}
1047 	up_write(&v9ses->rename_sem);
1048 	p9_client_clunk(newdirfid);
1049 
1050 clunk_olddir:
1051 	p9_client_clunk(olddirfid);
1052 
1053 done:
1054 	return retval;
1055 }
1056 
1057 /**
1058  * v9fs_vfs_getattr - retrieve file metadata
1059  * @path: Object to query
1060  * @stat: metadata structure to populate
1061  * @request_mask: Mask of STATX_xxx flags indicating the caller's interests
1062  * @flags: AT_STATX_xxx setting
1063  *
1064  */
1065 
1066 static int
1067 v9fs_vfs_getattr(const struct path *path, struct kstat *stat,
1068 		 u32 request_mask, unsigned int flags)
1069 {
1070 	struct dentry *dentry = path->dentry;
1071 	struct v9fs_session_info *v9ses;
1072 	struct p9_fid *fid;
1073 	struct p9_wstat *st;
1074 
1075 	p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
1076 	v9ses = v9fs_dentry2v9ses(dentry);
1077 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
1078 		generic_fillattr(d_inode(dentry), stat);
1079 		return 0;
1080 	}
1081 	fid = v9fs_fid_lookup(dentry);
1082 	if (IS_ERR(fid))
1083 		return PTR_ERR(fid);
1084 
1085 	st = p9_client_stat(fid);
1086 	if (IS_ERR(st))
1087 		return PTR_ERR(st);
1088 
1089 	v9fs_stat2inode(st, d_inode(dentry), dentry->d_sb, 0);
1090 	generic_fillattr(d_inode(dentry), stat);
1091 
1092 	p9stat_free(st);
1093 	kfree(st);
1094 	return 0;
1095 }
1096 
1097 /**
1098  * v9fs_vfs_setattr - set file metadata
1099  * @dentry: file whose metadata to set
1100  * @iattr: metadata assignment structure
1101  *
1102  */
1103 
1104 static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
1105 {
1106 	int retval;
1107 	struct v9fs_session_info *v9ses;
1108 	struct p9_fid *fid;
1109 	struct p9_wstat wstat;
1110 
1111 	p9_debug(P9_DEBUG_VFS, "\n");
1112 	retval = setattr_prepare(dentry, iattr);
1113 	if (retval)
1114 		return retval;
1115 
1116 	retval = -EPERM;
1117 	v9ses = v9fs_dentry2v9ses(dentry);
1118 	fid = v9fs_fid_lookup(dentry);
1119 	if(IS_ERR(fid))
1120 		return PTR_ERR(fid);
1121 
1122 	v9fs_blank_wstat(&wstat);
1123 	if (iattr->ia_valid & ATTR_MODE)
1124 		wstat.mode = unixmode2p9mode(v9ses, iattr->ia_mode);
1125 
1126 	if (iattr->ia_valid & ATTR_MTIME)
1127 		wstat.mtime = iattr->ia_mtime.tv_sec;
1128 
1129 	if (iattr->ia_valid & ATTR_ATIME)
1130 		wstat.atime = iattr->ia_atime.tv_sec;
1131 
1132 	if (iattr->ia_valid & ATTR_SIZE)
1133 		wstat.length = iattr->ia_size;
1134 
1135 	if (v9fs_proto_dotu(v9ses)) {
1136 		if (iattr->ia_valid & ATTR_UID)
1137 			wstat.n_uid = iattr->ia_uid;
1138 
1139 		if (iattr->ia_valid & ATTR_GID)
1140 			wstat.n_gid = iattr->ia_gid;
1141 	}
1142 
1143 	/* Write all dirty data */
1144 	if (d_is_reg(dentry))
1145 		filemap_write_and_wait(d_inode(dentry)->i_mapping);
1146 
1147 	retval = p9_client_wstat(fid, &wstat);
1148 	if (retval < 0)
1149 		return retval;
1150 
1151 	if ((iattr->ia_valid & ATTR_SIZE) &&
1152 	    iattr->ia_size != i_size_read(d_inode(dentry)))
1153 		truncate_setsize(d_inode(dentry), iattr->ia_size);
1154 
1155 	v9fs_invalidate_inode_attr(d_inode(dentry));
1156 
1157 	setattr_copy(d_inode(dentry), iattr);
1158 	mark_inode_dirty(d_inode(dentry));
1159 	return 0;
1160 }
1161 
1162 /**
1163  * v9fs_stat2inode - populate an inode structure with mistat info
1164  * @stat: Plan 9 metadata (mistat) structure
1165  * @inode: inode to populate
1166  * @sb: superblock of filesystem
1167  * @flags: control flags (e.g. V9FS_STAT2INODE_KEEP_ISIZE)
1168  *
1169  */
1170 
1171 void
1172 v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
1173 		 struct super_block *sb, unsigned int flags)
1174 {
1175 	umode_t mode;
1176 	char ext[32];
1177 	char tag_name[14];
1178 	unsigned int i_nlink;
1179 	struct v9fs_session_info *v9ses = sb->s_fs_info;
1180 	struct v9fs_inode *v9inode = V9FS_I(inode);
1181 
1182 	set_nlink(inode, 1);
1183 
1184 	inode->i_atime.tv_sec = stat->atime;
1185 	inode->i_mtime.tv_sec = stat->mtime;
1186 	inode->i_ctime.tv_sec = stat->mtime;
1187 
1188 	inode->i_uid = v9ses->dfltuid;
1189 	inode->i_gid = v9ses->dfltgid;
1190 
1191 	if (v9fs_proto_dotu(v9ses)) {
1192 		inode->i_uid = stat->n_uid;
1193 		inode->i_gid = stat->n_gid;
1194 	}
1195 	if ((S_ISREG(inode->i_mode)) || (S_ISDIR(inode->i_mode))) {
1196 		if (v9fs_proto_dotu(v9ses) && (stat->extension[0] != '\0')) {
1197 			/*
1198 			 * Hadlink support got added later to
1199 			 * to the .u extension. So there can be
1200 			 * server out there that doesn't support
1201 			 * this even with .u extension. So check
1202 			 * for non NULL stat->extension
1203 			 */
1204 			strlcpy(ext, stat->extension, sizeof(ext));
1205 			/* HARDLINKCOUNT %u */
1206 			sscanf(ext, "%13s %u", tag_name, &i_nlink);
1207 			if (!strncmp(tag_name, "HARDLINKCOUNT", 13))
1208 				set_nlink(inode, i_nlink);
1209 		}
1210 	}
1211 	mode = p9mode2perm(v9ses, stat);
1212 	mode |= inode->i_mode & ~S_IALLUGO;
1213 	inode->i_mode = mode;
1214 
1215 	if (!(flags & V9FS_STAT2INODE_KEEP_ISIZE))
1216 		v9fs_i_size_write(inode, stat->length);
1217 	/* not real number of blocks, but 512 byte ones ... */
1218 	inode->i_blocks = (stat->length + 512 - 1) >> 9;
1219 	v9inode->cache_validity &= ~V9FS_INO_INVALID_ATTR;
1220 }
1221 
1222 /**
1223  * v9fs_qid2ino - convert qid into inode number
1224  * @qid: qid to hash
1225  *
1226  * BUG: potential for inode number collisions?
1227  */
1228 
1229 ino_t v9fs_qid2ino(struct p9_qid *qid)
1230 {
1231 	u64 path = qid->path + 2;
1232 	ino_t i = 0;
1233 
1234 	if (sizeof(ino_t) == sizeof(path))
1235 		memcpy(&i, &path, sizeof(ino_t));
1236 	else
1237 		i = (ino_t) (path ^ (path >> 32));
1238 
1239 	return i;
1240 }
1241 
1242 /**
1243  * v9fs_vfs_get_link - follow a symlink path
1244  * @dentry: dentry for symlink
1245  * @inode: inode for symlink
1246  * @done: delayed call for when we are done with the return value
1247  */
1248 
1249 static const char *v9fs_vfs_get_link(struct dentry *dentry,
1250 				     struct inode *inode,
1251 				     struct delayed_call *done)
1252 {
1253 	struct v9fs_session_info *v9ses;
1254 	struct p9_fid *fid;
1255 	struct p9_wstat *st;
1256 	char *res;
1257 
1258 	if (!dentry)
1259 		return ERR_PTR(-ECHILD);
1260 
1261 	v9ses = v9fs_dentry2v9ses(dentry);
1262 	fid = v9fs_fid_lookup(dentry);
1263 	p9_debug(P9_DEBUG_VFS, "%pd\n", dentry);
1264 
1265 	if (IS_ERR(fid))
1266 		return ERR_CAST(fid);
1267 
1268 	if (!v9fs_proto_dotu(v9ses))
1269 		return ERR_PTR(-EBADF);
1270 
1271 	st = p9_client_stat(fid);
1272 	if (IS_ERR(st))
1273 		return ERR_CAST(st);
1274 
1275 	if (!(st->mode & P9_DMSYMLINK)) {
1276 		p9stat_free(st);
1277 		kfree(st);
1278 		return ERR_PTR(-EINVAL);
1279 	}
1280 	res = st->extension;
1281 	st->extension = NULL;
1282 	if (strlen(res) >= PATH_MAX)
1283 		res[PATH_MAX - 1] = '\0';
1284 
1285 	p9stat_free(st);
1286 	kfree(st);
1287 	set_delayed_call(done, kfree_link, res);
1288 	return res;
1289 }
1290 
1291 /**
1292  * v9fs_vfs_mkspecial - create a special file
1293  * @dir: inode to create special file in
1294  * @dentry: dentry to create
1295  * @perm: mode to create special file
1296  * @extension: 9p2000.u format extension string representing special file
1297  *
1298  */
1299 
1300 static int v9fs_vfs_mkspecial(struct inode *dir, struct dentry *dentry,
1301 	u32 perm, const char *extension)
1302 {
1303 	struct p9_fid *fid;
1304 	struct v9fs_session_info *v9ses;
1305 
1306 	v9ses = v9fs_inode2v9ses(dir);
1307 	if (!v9fs_proto_dotu(v9ses)) {
1308 		p9_debug(P9_DEBUG_ERROR, "not extended\n");
1309 		return -EPERM;
1310 	}
1311 
1312 	fid = v9fs_create(v9ses, dir, dentry, (char *) extension, perm,
1313 								P9_OREAD);
1314 	if (IS_ERR(fid))
1315 		return PTR_ERR(fid);
1316 
1317 	v9fs_invalidate_inode_attr(dir);
1318 	p9_client_clunk(fid);
1319 	return 0;
1320 }
1321 
1322 /**
1323  * v9fs_vfs_symlink - helper function to create symlinks
1324  * @dir: directory inode containing symlink
1325  * @dentry: dentry for symlink
1326  * @symname: symlink data
1327  *
1328  * See Also: 9P2000.u RFC for more information
1329  *
1330  */
1331 
1332 static int
1333 v9fs_vfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1334 {
1335 	p9_debug(P9_DEBUG_VFS, " %lu,%pd,%s\n",
1336 		 dir->i_ino, dentry, symname);
1337 
1338 	return v9fs_vfs_mkspecial(dir, dentry, P9_DMSYMLINK, symname);
1339 }
1340 
1341 #define U32_MAX_DIGITS 10
1342 
1343 /**
1344  * v9fs_vfs_link - create a hardlink
1345  * @old_dentry: dentry for file to link to
1346  * @dir: inode destination for new link
1347  * @dentry: dentry for link
1348  *
1349  */
1350 
1351 static int
1352 v9fs_vfs_link(struct dentry *old_dentry, struct inode *dir,
1353 	      struct dentry *dentry)
1354 {
1355 	int retval;
1356 	char name[1 + U32_MAX_DIGITS + 2]; /* sign + number + \n + \0 */
1357 	struct p9_fid *oldfid;
1358 
1359 	p9_debug(P9_DEBUG_VFS, " %lu,%pd,%pd\n",
1360 		 dir->i_ino, dentry, old_dentry);
1361 
1362 	oldfid = v9fs_fid_clone(old_dentry);
1363 	if (IS_ERR(oldfid))
1364 		return PTR_ERR(oldfid);
1365 
1366 	sprintf(name, "%d\n", oldfid->fid);
1367 	retval = v9fs_vfs_mkspecial(dir, dentry, P9_DMLINK, name);
1368 	if (!retval) {
1369 		v9fs_refresh_inode(oldfid, d_inode(old_dentry));
1370 		v9fs_invalidate_inode_attr(dir);
1371 	}
1372 	p9_client_clunk(oldfid);
1373 	return retval;
1374 }
1375 
1376 /**
1377  * v9fs_vfs_mknod - create a special file
1378  * @dir: inode destination for new link
1379  * @dentry: dentry for file
1380  * @mode: mode for creation
1381  * @rdev: device associated with special file
1382  *
1383  */
1384 
1385 static int
1386 v9fs_vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t rdev)
1387 {
1388 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
1389 	int retval;
1390 	char name[2 + U32_MAX_DIGITS + 1 + U32_MAX_DIGITS + 1];
1391 	u32 perm;
1392 
1393 	p9_debug(P9_DEBUG_VFS, " %lu,%pd mode: %hx MAJOR: %u MINOR: %u\n",
1394 		 dir->i_ino, dentry, mode,
1395 		 MAJOR(rdev), MINOR(rdev));
1396 
1397 	/* build extension */
1398 	if (S_ISBLK(mode))
1399 		sprintf(name, "b %u %u", MAJOR(rdev), MINOR(rdev));
1400 	else if (S_ISCHR(mode))
1401 		sprintf(name, "c %u %u", MAJOR(rdev), MINOR(rdev));
1402 	else
1403 		*name = 0;
1404 
1405 	perm = unixmode2p9mode(v9ses, mode);
1406 	retval = v9fs_vfs_mkspecial(dir, dentry, perm, name);
1407 
1408 	return retval;
1409 }
1410 
1411 int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode)
1412 {
1413 	int umode;
1414 	dev_t rdev;
1415 	struct p9_wstat *st;
1416 	struct v9fs_session_info *v9ses;
1417 	unsigned int flags;
1418 
1419 	v9ses = v9fs_inode2v9ses(inode);
1420 	st = p9_client_stat(fid);
1421 	if (IS_ERR(st))
1422 		return PTR_ERR(st);
1423 	/*
1424 	 * Don't update inode if the file type is different
1425 	 */
1426 	umode = p9mode2unixmode(v9ses, st, &rdev);
1427 	if ((inode->i_mode & S_IFMT) != (umode & S_IFMT))
1428 		goto out;
1429 
1430 	/*
1431 	 * We don't want to refresh inode->i_size,
1432 	 * because we may have cached data
1433 	 */
1434 	flags = (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) ?
1435 		V9FS_STAT2INODE_KEEP_ISIZE : 0;
1436 	v9fs_stat2inode(st, inode, inode->i_sb, flags);
1437 out:
1438 	p9stat_free(st);
1439 	kfree(st);
1440 	return 0;
1441 }
1442 
1443 static const struct inode_operations v9fs_dir_inode_operations_dotu = {
1444 	.create = v9fs_vfs_create,
1445 	.lookup = v9fs_vfs_lookup,
1446 	.atomic_open = v9fs_vfs_atomic_open,
1447 	.symlink = v9fs_vfs_symlink,
1448 	.link = v9fs_vfs_link,
1449 	.unlink = v9fs_vfs_unlink,
1450 	.mkdir = v9fs_vfs_mkdir,
1451 	.rmdir = v9fs_vfs_rmdir,
1452 	.mknod = v9fs_vfs_mknod,
1453 	.rename = v9fs_vfs_rename,
1454 	.getattr = v9fs_vfs_getattr,
1455 	.setattr = v9fs_vfs_setattr,
1456 };
1457 
1458 static const struct inode_operations v9fs_dir_inode_operations = {
1459 	.create = v9fs_vfs_create,
1460 	.lookup = v9fs_vfs_lookup,
1461 	.atomic_open = v9fs_vfs_atomic_open,
1462 	.unlink = v9fs_vfs_unlink,
1463 	.mkdir = v9fs_vfs_mkdir,
1464 	.rmdir = v9fs_vfs_rmdir,
1465 	.mknod = v9fs_vfs_mknod,
1466 	.rename = v9fs_vfs_rename,
1467 	.getattr = v9fs_vfs_getattr,
1468 	.setattr = v9fs_vfs_setattr,
1469 };
1470 
1471 static const struct inode_operations v9fs_file_inode_operations = {
1472 	.getattr = v9fs_vfs_getattr,
1473 	.setattr = v9fs_vfs_setattr,
1474 };
1475 
1476 static const struct inode_operations v9fs_symlink_inode_operations = {
1477 	.get_link = v9fs_vfs_get_link,
1478 	.getattr = v9fs_vfs_getattr,
1479 	.setattr = v9fs_vfs_setattr,
1480 };
1481 
1482