xref: /openbmc/linux/fs/9p/vfs_inode.c (revision 5bd8e16d)
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 %u %u", &type, &major, &minor);
151 		switch (type) {
152 		case 'c':
153 			res |= S_IFCHR;
154 			break;
155 		case 'b':
156 			res |= S_IFBLK;
157 			break;
158 		default:
159 			p9_debug(P9_DEBUG_ERROR, "Unknown special type %c %s\n",
160 				 type, stat->extension);
161 		};
162 		*rdev = MKDEV(major, minor);
163 	} else
164 		res |= S_IFREG;
165 
166 	return res;
167 }
168 
169 /**
170  * v9fs_uflags2omode- convert posix open flags to plan 9 mode bits
171  * @uflags: flags to convert
172  * @extended: if .u extensions are active
173  */
174 
175 int v9fs_uflags2omode(int uflags, int extended)
176 {
177 	int ret;
178 
179 	ret = 0;
180 	switch (uflags&3) {
181 	default:
182 	case O_RDONLY:
183 		ret = P9_OREAD;
184 		break;
185 
186 	case O_WRONLY:
187 		ret = P9_OWRITE;
188 		break;
189 
190 	case O_RDWR:
191 		ret = P9_ORDWR;
192 		break;
193 	}
194 
195 	if (extended) {
196 		if (uflags & O_EXCL)
197 			ret |= P9_OEXCL;
198 
199 		if (uflags & O_APPEND)
200 			ret |= P9_OAPPEND;
201 	}
202 
203 	return ret;
204 }
205 
206 /**
207  * v9fs_blank_wstat - helper function to setup a 9P stat structure
208  * @wstat: structure to initialize
209  *
210  */
211 
212 void
213 v9fs_blank_wstat(struct p9_wstat *wstat)
214 {
215 	wstat->type = ~0;
216 	wstat->dev = ~0;
217 	wstat->qid.type = ~0;
218 	wstat->qid.version = ~0;
219 	*((long long *)&wstat->qid.path) = ~0;
220 	wstat->mode = ~0;
221 	wstat->atime = ~0;
222 	wstat->mtime = ~0;
223 	wstat->length = ~0;
224 	wstat->name = NULL;
225 	wstat->uid = NULL;
226 	wstat->gid = NULL;
227 	wstat->muid = NULL;
228 	wstat->n_uid = INVALID_UID;
229 	wstat->n_gid = INVALID_GID;
230 	wstat->n_muid = INVALID_UID;
231 	wstat->extension = NULL;
232 }
233 
234 /**
235  * v9fs_alloc_inode - helper function to allocate an inode
236  *
237  */
238 struct inode *v9fs_alloc_inode(struct super_block *sb)
239 {
240 	struct v9fs_inode *v9inode;
241 	v9inode = (struct v9fs_inode *)kmem_cache_alloc(v9fs_inode_cache,
242 							GFP_KERNEL);
243 	if (!v9inode)
244 		return NULL;
245 #ifdef CONFIG_9P_FSCACHE
246 	v9inode->fscache = NULL;
247 	spin_lock_init(&v9inode->fscache_lock);
248 #endif
249 	v9inode->writeback_fid = NULL;
250 	v9inode->cache_validity = 0;
251 	mutex_init(&v9inode->v_mutex);
252 	return &v9inode->vfs_inode;
253 }
254 
255 /**
256  * v9fs_destroy_inode - destroy an inode
257  *
258  */
259 
260 static void v9fs_i_callback(struct rcu_head *head)
261 {
262 	struct inode *inode = container_of(head, struct inode, i_rcu);
263 	kmem_cache_free(v9fs_inode_cache, V9FS_I(inode));
264 }
265 
266 void v9fs_destroy_inode(struct inode *inode)
267 {
268 	call_rcu(&inode->i_rcu, v9fs_i_callback);
269 }
270 
271 int v9fs_init_inode(struct v9fs_session_info *v9ses,
272 		    struct inode *inode, umode_t mode, dev_t rdev)
273 {
274 	int err = 0;
275 
276 	inode_init_owner(inode, NULL, mode);
277 	inode->i_blocks = 0;
278 	inode->i_rdev = rdev;
279 	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
280 	inode->i_mapping->a_ops = &v9fs_addr_operations;
281 
282 	switch (mode & S_IFMT) {
283 	case S_IFIFO:
284 	case S_IFBLK:
285 	case S_IFCHR:
286 	case S_IFSOCK:
287 		if (v9fs_proto_dotl(v9ses)) {
288 			inode->i_op = &v9fs_file_inode_operations_dotl;
289 		} else if (v9fs_proto_dotu(v9ses)) {
290 			inode->i_op = &v9fs_file_inode_operations;
291 		} else {
292 			p9_debug(P9_DEBUG_ERROR,
293 				 "special files without extended mode\n");
294 			err = -EINVAL;
295 			goto error;
296 		}
297 		init_special_inode(inode, inode->i_mode, inode->i_rdev);
298 		break;
299 	case S_IFREG:
300 		if (v9fs_proto_dotl(v9ses)) {
301 			inode->i_op = &v9fs_file_inode_operations_dotl;
302 			if (v9ses->cache)
303 				inode->i_fop =
304 					&v9fs_cached_file_operations_dotl;
305 			else
306 				inode->i_fop = &v9fs_file_operations_dotl;
307 		} else {
308 			inode->i_op = &v9fs_file_inode_operations;
309 			if (v9ses->cache)
310 				inode->i_fop = &v9fs_cached_file_operations;
311 			else
312 				inode->i_fop = &v9fs_file_operations;
313 		}
314 
315 		break;
316 	case S_IFLNK:
317 		if (!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)) {
318 			p9_debug(P9_DEBUG_ERROR,
319 				 "extended modes used with legacy protocol\n");
320 			err = -EINVAL;
321 			goto error;
322 		}
323 
324 		if (v9fs_proto_dotl(v9ses))
325 			inode->i_op = &v9fs_symlink_inode_operations_dotl;
326 		else
327 			inode->i_op = &v9fs_symlink_inode_operations;
328 
329 		break;
330 	case S_IFDIR:
331 		inc_nlink(inode);
332 		if (v9fs_proto_dotl(v9ses))
333 			inode->i_op = &v9fs_dir_inode_operations_dotl;
334 		else if (v9fs_proto_dotu(v9ses))
335 			inode->i_op = &v9fs_dir_inode_operations_dotu;
336 		else
337 			inode->i_op = &v9fs_dir_inode_operations;
338 
339 		if (v9fs_proto_dotl(v9ses))
340 			inode->i_fop = &v9fs_dir_operations_dotl;
341 		else
342 			inode->i_fop = &v9fs_dir_operations;
343 
344 		break;
345 	default:
346 		p9_debug(P9_DEBUG_ERROR, "BAD mode 0x%hx S_IFMT 0x%x\n",
347 			 mode, mode & S_IFMT);
348 		err = -EINVAL;
349 		goto error;
350 	}
351 error:
352 	return err;
353 
354 }
355 
356 /**
357  * v9fs_get_inode - helper function to setup an inode
358  * @sb: superblock
359  * @mode: mode to setup inode with
360  *
361  */
362 
363 struct inode *v9fs_get_inode(struct super_block *sb, umode_t mode, dev_t rdev)
364 {
365 	int err;
366 	struct inode *inode;
367 	struct v9fs_session_info *v9ses = sb->s_fs_info;
368 
369 	p9_debug(P9_DEBUG_VFS, "super block: %p mode: %ho\n", sb, mode);
370 
371 	inode = new_inode(sb);
372 	if (!inode) {
373 		pr_warn("%s (%d): Problem allocating inode\n",
374 			__func__, task_pid_nr(current));
375 		return ERR_PTR(-ENOMEM);
376 	}
377 	err = v9fs_init_inode(v9ses, inode, mode, rdev);
378 	if (err) {
379 		iput(inode);
380 		return ERR_PTR(err);
381 	}
382 	return inode;
383 }
384 
385 /*
386 static struct v9fs_fid*
387 v9fs_clone_walk(struct v9fs_session_info *v9ses, u32 fid, struct dentry *dentry)
388 {
389 	int err;
390 	int nfid;
391 	struct v9fs_fid *ret;
392 	struct v9fs_fcall *fcall;
393 
394 	nfid = v9fs_get_idpool(&v9ses->fidpool);
395 	if (nfid < 0) {
396 		eprintk(KERN_WARNING, "no free fids available\n");
397 		return ERR_PTR(-ENOSPC);
398 	}
399 
400 	err = v9fs_t_walk(v9ses, fid, nfid, (char *) dentry->d_name.name,
401 		&fcall);
402 
403 	if (err < 0) {
404 		if (fcall && fcall->id == RWALK)
405 			goto clunk_fid;
406 
407 		PRINT_FCALL_ERROR("walk error", fcall);
408 		v9fs_put_idpool(nfid, &v9ses->fidpool);
409 		goto error;
410 	}
411 
412 	kfree(fcall);
413 	fcall = NULL;
414 	ret = v9fs_fid_create(v9ses, nfid);
415 	if (!ret) {
416 		err = -ENOMEM;
417 		goto clunk_fid;
418 	}
419 
420 	err = v9fs_fid_insert(ret, dentry);
421 	if (err < 0) {
422 		v9fs_fid_destroy(ret);
423 		goto clunk_fid;
424 	}
425 
426 	return ret;
427 
428 clunk_fid:
429 	v9fs_t_clunk(v9ses, nfid);
430 
431 error:
432 	kfree(fcall);
433 	return ERR_PTR(err);
434 }
435 */
436 
437 
438 /**
439  * v9fs_clear_inode - release an inode
440  * @inode: inode to release
441  *
442  */
443 void v9fs_evict_inode(struct inode *inode)
444 {
445 	struct v9fs_inode *v9inode = V9FS_I(inode);
446 
447 	truncate_inode_pages(inode->i_mapping, 0);
448 	clear_inode(inode);
449 	filemap_fdatawrite(inode->i_mapping);
450 
451 #ifdef CONFIG_9P_FSCACHE
452 	v9fs_cache_inode_put_cookie(inode);
453 #endif
454 	/* clunk the fid stashed in writeback_fid */
455 	if (v9inode->writeback_fid) {
456 		p9_client_clunk(v9inode->writeback_fid);
457 		v9inode->writeback_fid = NULL;
458 	}
459 }
460 
461 static int v9fs_test_inode(struct inode *inode, void *data)
462 {
463 	int umode;
464 	dev_t rdev;
465 	struct v9fs_inode *v9inode = V9FS_I(inode);
466 	struct p9_wstat *st = (struct p9_wstat *)data;
467 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
468 
469 	umode = p9mode2unixmode(v9ses, st, &rdev);
470 	/* don't match inode of different type */
471 	if ((inode->i_mode & S_IFMT) != (umode & S_IFMT))
472 		return 0;
473 
474 	/* compare qid details */
475 	if (memcmp(&v9inode->qid.version,
476 		   &st->qid.version, sizeof(v9inode->qid.version)))
477 		return 0;
478 
479 	if (v9inode->qid.type != st->qid.type)
480 		return 0;
481 	return 1;
482 }
483 
484 static int v9fs_test_new_inode(struct inode *inode, void *data)
485 {
486 	return 0;
487 }
488 
489 static int v9fs_set_inode(struct inode *inode,  void *data)
490 {
491 	struct v9fs_inode *v9inode = V9FS_I(inode);
492 	struct p9_wstat *st = (struct p9_wstat *)data;
493 
494 	memcpy(&v9inode->qid, &st->qid, sizeof(st->qid));
495 	return 0;
496 }
497 
498 static struct inode *v9fs_qid_iget(struct super_block *sb,
499 				   struct p9_qid *qid,
500 				   struct p9_wstat *st,
501 				   int new)
502 {
503 	dev_t rdev;
504 	int retval;
505 	umode_t umode;
506 	unsigned long i_ino;
507 	struct inode *inode;
508 	struct v9fs_session_info *v9ses = sb->s_fs_info;
509 	int (*test)(struct inode *, void *);
510 
511 	if (new)
512 		test = v9fs_test_new_inode;
513 	else
514 		test = v9fs_test_inode;
515 
516 	i_ino = v9fs_qid2ino(qid);
517 	inode = iget5_locked(sb, i_ino, test, v9fs_set_inode, st);
518 	if (!inode)
519 		return ERR_PTR(-ENOMEM);
520 	if (!(inode->i_state & I_NEW))
521 		return inode;
522 	/*
523 	 * initialize the inode with the stat info
524 	 * FIXME!! we may need support for stale inodes
525 	 * later.
526 	 */
527 	inode->i_ino = i_ino;
528 	umode = p9mode2unixmode(v9ses, st, &rdev);
529 	retval = v9fs_init_inode(v9ses, inode, umode, rdev);
530 	if (retval)
531 		goto error;
532 
533 	v9fs_stat2inode(st, inode, sb);
534 #ifdef CONFIG_9P_FSCACHE
535 	v9fs_cache_inode_get_cookie(inode);
536 #endif
537 	unlock_new_inode(inode);
538 	return inode;
539 error:
540 	unlock_new_inode(inode);
541 	iput(inode);
542 	return ERR_PTR(retval);
543 
544 }
545 
546 struct inode *
547 v9fs_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
548 		    struct super_block *sb, int new)
549 {
550 	struct p9_wstat *st;
551 	struct inode *inode = NULL;
552 
553 	st = p9_client_stat(fid);
554 	if (IS_ERR(st))
555 		return ERR_CAST(st);
556 
557 	inode = v9fs_qid_iget(sb, &st->qid, st, new);
558 	p9stat_free(st);
559 	kfree(st);
560 	return inode;
561 }
562 
563 /**
564  * v9fs_at_to_dotl_flags- convert Linux specific AT flags to
565  * plan 9 AT flag.
566  * @flags: flags to convert
567  */
568 static int v9fs_at_to_dotl_flags(int flags)
569 {
570 	int rflags = 0;
571 	if (flags & AT_REMOVEDIR)
572 		rflags |= P9_DOTL_AT_REMOVEDIR;
573 	return rflags;
574 }
575 
576 /**
577  * v9fs_remove - helper function to remove files and directories
578  * @dir: directory inode that is being deleted
579  * @dentry:  dentry that is being deleted
580  * @rmdir: removing a directory
581  *
582  */
583 
584 static int v9fs_remove(struct inode *dir, struct dentry *dentry, int flags)
585 {
586 	struct inode *inode;
587 	int retval = -EOPNOTSUPP;
588 	struct p9_fid *v9fid, *dfid;
589 	struct v9fs_session_info *v9ses;
590 
591 	p9_debug(P9_DEBUG_VFS, "inode: %p dentry: %p rmdir: %x\n",
592 		 dir, dentry, flags);
593 
594 	v9ses = v9fs_inode2v9ses(dir);
595 	inode = dentry->d_inode;
596 	dfid = v9fs_fid_lookup(dentry->d_parent);
597 	if (IS_ERR(dfid)) {
598 		retval = PTR_ERR(dfid);
599 		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", retval);
600 		return retval;
601 	}
602 	if (v9fs_proto_dotl(v9ses))
603 		retval = p9_client_unlinkat(dfid, dentry->d_name.name,
604 					    v9fs_at_to_dotl_flags(flags));
605 	if (retval == -EOPNOTSUPP) {
606 		/* Try the one based on path */
607 		v9fid = v9fs_fid_clone(dentry);
608 		if (IS_ERR(v9fid))
609 			return PTR_ERR(v9fid);
610 		retval = p9_client_remove(v9fid);
611 	}
612 	if (!retval) {
613 		/*
614 		 * directories on unlink should have zero
615 		 * link count
616 		 */
617 		if (flags & AT_REMOVEDIR) {
618 			clear_nlink(inode);
619 			drop_nlink(dir);
620 		} else
621 			drop_nlink(inode);
622 
623 		v9fs_invalidate_inode_attr(inode);
624 		v9fs_invalidate_inode_attr(dir);
625 	}
626 	return retval;
627 }
628 
629 /**
630  * v9fs_create - Create a file
631  * @v9ses: session information
632  * @dir: directory that dentry is being created in
633  * @dentry:  dentry that is being created
634  * @extension: 9p2000.u extension string to support devices, etc.
635  * @perm: create permissions
636  * @mode: open mode
637  *
638  */
639 static struct p9_fid *
640 v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
641 		struct dentry *dentry, char *extension, u32 perm, u8 mode)
642 {
643 	int err;
644 	char *name;
645 	struct p9_fid *dfid, *ofid, *fid;
646 	struct inode *inode;
647 
648 	p9_debug(P9_DEBUG_VFS, "name %s\n", dentry->d_name.name);
649 
650 	err = 0;
651 	ofid = NULL;
652 	fid = NULL;
653 	name = (char *) dentry->d_name.name;
654 	dfid = v9fs_fid_lookup(dentry->d_parent);
655 	if (IS_ERR(dfid)) {
656 		err = PTR_ERR(dfid);
657 		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", err);
658 		return ERR_PTR(err);
659 	}
660 
661 	/* clone a fid to use for creation */
662 	ofid = p9_client_walk(dfid, 0, NULL, 1);
663 	if (IS_ERR(ofid)) {
664 		err = PTR_ERR(ofid);
665 		p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n", err);
666 		return ERR_PTR(err);
667 	}
668 
669 	err = p9_client_fcreate(ofid, name, perm, mode, extension);
670 	if (err < 0) {
671 		p9_debug(P9_DEBUG_VFS, "p9_client_fcreate failed %d\n", err);
672 		goto error;
673 	}
674 
675 	if (!(perm & P9_DMLINK)) {
676 		/* now walk from the parent so we can get unopened fid */
677 		fid = p9_client_walk(dfid, 1, &name, 1);
678 		if (IS_ERR(fid)) {
679 			err = PTR_ERR(fid);
680 			p9_debug(P9_DEBUG_VFS,
681 				   "p9_client_walk failed %d\n", err);
682 			fid = NULL;
683 			goto error;
684 		}
685 		/*
686 		 * instantiate inode and assign the unopened fid to the dentry
687 		 */
688 		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
689 		if (IS_ERR(inode)) {
690 			err = PTR_ERR(inode);
691 			p9_debug(P9_DEBUG_VFS,
692 				   "inode creation failed %d\n", err);
693 			goto error;
694 		}
695 		v9fs_fid_add(dentry, fid);
696 		d_instantiate(dentry, inode);
697 	}
698 	return ofid;
699 error:
700 	if (ofid)
701 		p9_client_clunk(ofid);
702 
703 	if (fid)
704 		p9_client_clunk(fid);
705 
706 	return ERR_PTR(err);
707 }
708 
709 /**
710  * v9fs_vfs_create - VFS hook to create a regular file
711  *
712  * open(.., O_CREAT) is handled in v9fs_vfs_atomic_open().  This is only called
713  * for mknod(2).
714  *
715  * @dir: directory inode that is being created
716  * @dentry:  dentry that is being deleted
717  * @mode: create permissions
718  *
719  */
720 
721 static int
722 v9fs_vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
723 		bool excl)
724 {
725 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
726 	u32 perm = unixmode2p9mode(v9ses, mode);
727 	struct p9_fid *fid;
728 
729 	/* P9_OEXCL? */
730 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_ORDWR);
731 	if (IS_ERR(fid))
732 		return PTR_ERR(fid);
733 
734 	v9fs_invalidate_inode_attr(dir);
735 	p9_client_clunk(fid);
736 
737 	return 0;
738 }
739 
740 /**
741  * v9fs_vfs_mkdir - VFS mkdir hook to create a directory
742  * @dir:  inode that is being unlinked
743  * @dentry: dentry that is being unlinked
744  * @mode: mode for new directory
745  *
746  */
747 
748 static int v9fs_vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
749 {
750 	int err;
751 	u32 perm;
752 	struct p9_fid *fid;
753 	struct v9fs_session_info *v9ses;
754 
755 	p9_debug(P9_DEBUG_VFS, "name %s\n", dentry->d_name.name);
756 	err = 0;
757 	v9ses = v9fs_inode2v9ses(dir);
758 	perm = unixmode2p9mode(v9ses, mode | S_IFDIR);
759 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_OREAD);
760 	if (IS_ERR(fid)) {
761 		err = PTR_ERR(fid);
762 		fid = NULL;
763 	} else {
764 		inc_nlink(dir);
765 		v9fs_invalidate_inode_attr(dir);
766 	}
767 
768 	if (fid)
769 		p9_client_clunk(fid);
770 
771 	return err;
772 }
773 
774 /**
775  * v9fs_vfs_lookup - VFS lookup hook to "walk" to a new inode
776  * @dir:  inode that is being walked from
777  * @dentry: dentry that is being walked to?
778  * @nameidata: path data
779  *
780  */
781 
782 struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
783 				      unsigned int flags)
784 {
785 	struct dentry *res;
786 	struct super_block *sb;
787 	struct v9fs_session_info *v9ses;
788 	struct p9_fid *dfid, *fid;
789 	struct inode *inode;
790 	char *name;
791 
792 	p9_debug(P9_DEBUG_VFS, "dir: %p dentry: (%s) %p flags: %x\n",
793 		 dir, dentry->d_name.name, dentry, flags);
794 
795 	if (dentry->d_name.len > NAME_MAX)
796 		return ERR_PTR(-ENAMETOOLONG);
797 
798 	sb = dir->i_sb;
799 	v9ses = v9fs_inode2v9ses(dir);
800 	/* We can walk d_parent because we hold the dir->i_mutex */
801 	dfid = v9fs_fid_lookup(dentry->d_parent);
802 	if (IS_ERR(dfid))
803 		return ERR_CAST(dfid);
804 
805 	name = (char *) dentry->d_name.name;
806 	fid = p9_client_walk(dfid, 1, &name, 1);
807 	if (IS_ERR(fid)) {
808 		if (fid == ERR_PTR(-ENOENT)) {
809 			d_add(dentry, NULL);
810 			return NULL;
811 		}
812 		return ERR_CAST(fid);
813 	}
814 	/*
815 	 * Make sure we don't use a wrong inode due to parallel
816 	 * unlink. For cached mode create calls request for new
817 	 * inode. But with cache disabled, lookup should do this.
818 	 */
819 	if (v9ses->cache)
820 		inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
821 	else
822 		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
823 	if (IS_ERR(inode)) {
824 		p9_client_clunk(fid);
825 		return ERR_CAST(inode);
826 	}
827 	/*
828 	 * If we had a rename on the server and a parallel lookup
829 	 * for the new name, then make sure we instantiate with
830 	 * the new name. ie look up for a/b, while on server somebody
831 	 * moved b under k and client parallely did a lookup for
832 	 * k/b.
833 	 */
834 	res = d_materialise_unique(dentry, inode);
835 	if (!res)
836 		v9fs_fid_add(dentry, fid);
837 	else if (!IS_ERR(res))
838 		v9fs_fid_add(res, fid);
839 	else
840 		p9_client_clunk(fid);
841 	return res;
842 }
843 
844 static int
845 v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
846 		     struct file *file, unsigned flags, umode_t mode,
847 		     int *opened)
848 {
849 	int err;
850 	u32 perm;
851 	struct v9fs_inode *v9inode;
852 	struct v9fs_session_info *v9ses;
853 	struct p9_fid *fid, *inode_fid;
854 	struct dentry *res = NULL;
855 
856 	if (d_unhashed(dentry)) {
857 		res = v9fs_vfs_lookup(dir, dentry, 0);
858 		if (IS_ERR(res))
859 			return PTR_ERR(res);
860 
861 		if (res)
862 			dentry = res;
863 	}
864 
865 	/* Only creates */
866 	if (!(flags & O_CREAT) || dentry->d_inode)
867 		return finish_no_open(file, res);
868 
869 	err = 0;
870 	fid = NULL;
871 	v9ses = v9fs_inode2v9ses(dir);
872 	perm = unixmode2p9mode(v9ses, mode);
873 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm,
874 				v9fs_uflags2omode(flags,
875 						v9fs_proto_dotu(v9ses)));
876 	if (IS_ERR(fid)) {
877 		err = PTR_ERR(fid);
878 		fid = NULL;
879 		goto error;
880 	}
881 
882 	v9fs_invalidate_inode_attr(dir);
883 	v9inode = V9FS_I(dentry->d_inode);
884 	mutex_lock(&v9inode->v_mutex);
885 	if (v9ses->cache && !v9inode->writeback_fid &&
886 	    ((flags & O_ACCMODE) != O_RDONLY)) {
887 		/*
888 		 * clone a fid and add it to writeback_fid
889 		 * we do it during open time instead of
890 		 * page dirty time via write_begin/page_mkwrite
891 		 * because we want write after unlink usecase
892 		 * to work.
893 		 */
894 		inode_fid = v9fs_writeback_fid(dentry);
895 		if (IS_ERR(inode_fid)) {
896 			err = PTR_ERR(inode_fid);
897 			mutex_unlock(&v9inode->v_mutex);
898 			goto error;
899 		}
900 		v9inode->writeback_fid = (void *) inode_fid;
901 	}
902 	mutex_unlock(&v9inode->v_mutex);
903 	err = finish_open(file, dentry, generic_file_open, opened);
904 	if (err)
905 		goto error;
906 
907 	file->private_data = fid;
908 #ifdef CONFIG_9P_FSCACHE
909 	if (v9ses->cache)
910 		v9fs_cache_inode_set_cookie(dentry->d_inode, file);
911 #endif
912 
913 	*opened |= FILE_CREATED;
914 out:
915 	dput(res);
916 	return err;
917 
918 error:
919 	if (fid)
920 		p9_client_clunk(fid);
921 	goto out;
922 }
923 
924 /**
925  * v9fs_vfs_unlink - VFS unlink hook to delete an inode
926  * @i:  inode that is being unlinked
927  * @d: dentry that is being unlinked
928  *
929  */
930 
931 int v9fs_vfs_unlink(struct inode *i, struct dentry *d)
932 {
933 	return v9fs_remove(i, d, 0);
934 }
935 
936 /**
937  * v9fs_vfs_rmdir - VFS unlink hook to delete a directory
938  * @i:  inode that is being unlinked
939  * @d: dentry that is being unlinked
940  *
941  */
942 
943 int v9fs_vfs_rmdir(struct inode *i, struct dentry *d)
944 {
945 	return v9fs_remove(i, d, AT_REMOVEDIR);
946 }
947 
948 /**
949  * v9fs_vfs_rename - VFS hook to rename an inode
950  * @old_dir:  old dir inode
951  * @old_dentry: old dentry
952  * @new_dir: new dir inode
953  * @new_dentry: new dentry
954  *
955  */
956 
957 int
958 v9fs_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
959 		struct inode *new_dir, struct dentry *new_dentry)
960 {
961 	int retval;
962 	struct inode *old_inode;
963 	struct inode *new_inode;
964 	struct v9fs_session_info *v9ses;
965 	struct p9_fid *oldfid;
966 	struct p9_fid *olddirfid;
967 	struct p9_fid *newdirfid;
968 	struct p9_wstat wstat;
969 
970 	p9_debug(P9_DEBUG_VFS, "\n");
971 	retval = 0;
972 	old_inode = old_dentry->d_inode;
973 	new_inode = new_dentry->d_inode;
974 	v9ses = v9fs_inode2v9ses(old_inode);
975 	oldfid = v9fs_fid_lookup(old_dentry);
976 	if (IS_ERR(oldfid))
977 		return PTR_ERR(oldfid);
978 
979 	olddirfid = v9fs_fid_clone(old_dentry->d_parent);
980 	if (IS_ERR(olddirfid)) {
981 		retval = PTR_ERR(olddirfid);
982 		goto done;
983 	}
984 
985 	newdirfid = v9fs_fid_clone(new_dentry->d_parent);
986 	if (IS_ERR(newdirfid)) {
987 		retval = PTR_ERR(newdirfid);
988 		goto clunk_olddir;
989 	}
990 
991 	down_write(&v9ses->rename_sem);
992 	if (v9fs_proto_dotl(v9ses)) {
993 		retval = p9_client_renameat(olddirfid, old_dentry->d_name.name,
994 					    newdirfid, new_dentry->d_name.name);
995 		if (retval == -EOPNOTSUPP)
996 			retval = p9_client_rename(oldfid, newdirfid,
997 						  new_dentry->d_name.name);
998 		if (retval != -EOPNOTSUPP)
999 			goto clunk_newdir;
1000 	}
1001 	if (old_dentry->d_parent != new_dentry->d_parent) {
1002 		/*
1003 		 * 9P .u can only handle file rename in the same directory
1004 		 */
1005 
1006 		p9_debug(P9_DEBUG_ERROR, "old dir and new dir are different\n");
1007 		retval = -EXDEV;
1008 		goto clunk_newdir;
1009 	}
1010 	v9fs_blank_wstat(&wstat);
1011 	wstat.muid = v9ses->uname;
1012 	wstat.name = (char *) new_dentry->d_name.name;
1013 	retval = p9_client_wstat(oldfid, &wstat);
1014 
1015 clunk_newdir:
1016 	if (!retval) {
1017 		if (new_inode) {
1018 			if (S_ISDIR(new_inode->i_mode))
1019 				clear_nlink(new_inode);
1020 			else
1021 				drop_nlink(new_inode);
1022 		}
1023 		if (S_ISDIR(old_inode->i_mode)) {
1024 			if (!new_inode)
1025 				inc_nlink(new_dir);
1026 			drop_nlink(old_dir);
1027 		}
1028 		v9fs_invalidate_inode_attr(old_inode);
1029 		v9fs_invalidate_inode_attr(old_dir);
1030 		v9fs_invalidate_inode_attr(new_dir);
1031 
1032 		/* successful rename */
1033 		d_move(old_dentry, new_dentry);
1034 	}
1035 	up_write(&v9ses->rename_sem);
1036 	p9_client_clunk(newdirfid);
1037 
1038 clunk_olddir:
1039 	p9_client_clunk(olddirfid);
1040 
1041 done:
1042 	return retval;
1043 }
1044 
1045 /**
1046  * v9fs_vfs_getattr - retrieve file metadata
1047  * @mnt: mount information
1048  * @dentry: file to get attributes on
1049  * @stat: metadata structure to populate
1050  *
1051  */
1052 
1053 static int
1054 v9fs_vfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
1055 		 struct kstat *stat)
1056 {
1057 	struct v9fs_session_info *v9ses;
1058 	struct p9_fid *fid;
1059 	struct p9_wstat *st;
1060 
1061 	p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
1062 	v9ses = v9fs_dentry2v9ses(dentry);
1063 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
1064 		generic_fillattr(dentry->d_inode, stat);
1065 		return 0;
1066 	}
1067 	fid = v9fs_fid_lookup(dentry);
1068 	if (IS_ERR(fid))
1069 		return PTR_ERR(fid);
1070 
1071 	st = p9_client_stat(fid);
1072 	if (IS_ERR(st))
1073 		return PTR_ERR(st);
1074 
1075 	v9fs_stat2inode(st, dentry->d_inode, dentry->d_inode->i_sb);
1076 	generic_fillattr(dentry->d_inode, stat);
1077 
1078 	p9stat_free(st);
1079 	kfree(st);
1080 	return 0;
1081 }
1082 
1083 /**
1084  * v9fs_vfs_setattr - set file metadata
1085  * @dentry: file whose metadata to set
1086  * @iattr: metadata assignment structure
1087  *
1088  */
1089 
1090 static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
1091 {
1092 	int retval;
1093 	struct v9fs_session_info *v9ses;
1094 	struct p9_fid *fid;
1095 	struct p9_wstat wstat;
1096 
1097 	p9_debug(P9_DEBUG_VFS, "\n");
1098 	retval = inode_change_ok(dentry->d_inode, iattr);
1099 	if (retval)
1100 		return retval;
1101 
1102 	retval = -EPERM;
1103 	v9ses = v9fs_dentry2v9ses(dentry);
1104 	fid = v9fs_fid_lookup(dentry);
1105 	if(IS_ERR(fid))
1106 		return PTR_ERR(fid);
1107 
1108 	v9fs_blank_wstat(&wstat);
1109 	if (iattr->ia_valid & ATTR_MODE)
1110 		wstat.mode = unixmode2p9mode(v9ses, iattr->ia_mode);
1111 
1112 	if (iattr->ia_valid & ATTR_MTIME)
1113 		wstat.mtime = iattr->ia_mtime.tv_sec;
1114 
1115 	if (iattr->ia_valid & ATTR_ATIME)
1116 		wstat.atime = iattr->ia_atime.tv_sec;
1117 
1118 	if (iattr->ia_valid & ATTR_SIZE)
1119 		wstat.length = iattr->ia_size;
1120 
1121 	if (v9fs_proto_dotu(v9ses)) {
1122 		if (iattr->ia_valid & ATTR_UID)
1123 			wstat.n_uid = iattr->ia_uid;
1124 
1125 		if (iattr->ia_valid & ATTR_GID)
1126 			wstat.n_gid = iattr->ia_gid;
1127 	}
1128 
1129 	/* Write all dirty data */
1130 	if (S_ISREG(dentry->d_inode->i_mode))
1131 		filemap_write_and_wait(dentry->d_inode->i_mapping);
1132 
1133 	retval = p9_client_wstat(fid, &wstat);
1134 	if (retval < 0)
1135 		return retval;
1136 
1137 	if ((iattr->ia_valid & ATTR_SIZE) &&
1138 	    iattr->ia_size != i_size_read(dentry->d_inode))
1139 		truncate_setsize(dentry->d_inode, iattr->ia_size);
1140 
1141 	v9fs_invalidate_inode_attr(dentry->d_inode);
1142 
1143 	setattr_copy(dentry->d_inode, iattr);
1144 	mark_inode_dirty(dentry->d_inode);
1145 	return 0;
1146 }
1147 
1148 /**
1149  * v9fs_stat2inode - populate an inode structure with mistat info
1150  * @stat: Plan 9 metadata (mistat) structure
1151  * @inode: inode to populate
1152  * @sb: superblock of filesystem
1153  *
1154  */
1155 
1156 void
1157 v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
1158 	struct super_block *sb)
1159 {
1160 	umode_t mode;
1161 	char ext[32];
1162 	char tag_name[14];
1163 	unsigned int i_nlink;
1164 	struct v9fs_session_info *v9ses = sb->s_fs_info;
1165 	struct v9fs_inode *v9inode = V9FS_I(inode);
1166 
1167 	set_nlink(inode, 1);
1168 
1169 	inode->i_atime.tv_sec = stat->atime;
1170 	inode->i_mtime.tv_sec = stat->mtime;
1171 	inode->i_ctime.tv_sec = stat->mtime;
1172 
1173 	inode->i_uid = v9ses->dfltuid;
1174 	inode->i_gid = v9ses->dfltgid;
1175 
1176 	if (v9fs_proto_dotu(v9ses)) {
1177 		inode->i_uid = stat->n_uid;
1178 		inode->i_gid = stat->n_gid;
1179 	}
1180 	if ((S_ISREG(inode->i_mode)) || (S_ISDIR(inode->i_mode))) {
1181 		if (v9fs_proto_dotu(v9ses) && (stat->extension[0] != '\0')) {
1182 			/*
1183 			 * Hadlink support got added later to
1184 			 * to the .u extension. So there can be
1185 			 * server out there that doesn't support
1186 			 * this even with .u extension. So check
1187 			 * for non NULL stat->extension
1188 			 */
1189 			strlcpy(ext, stat->extension, sizeof(ext));
1190 			/* HARDLINKCOUNT %u */
1191 			sscanf(ext, "%13s %u", tag_name, &i_nlink);
1192 			if (!strncmp(tag_name, "HARDLINKCOUNT", 13))
1193 				set_nlink(inode, i_nlink);
1194 		}
1195 	}
1196 	mode = p9mode2perm(v9ses, stat);
1197 	mode |= inode->i_mode & ~S_IALLUGO;
1198 	inode->i_mode = mode;
1199 	i_size_write(inode, stat->length);
1200 
1201 	/* not real number of blocks, but 512 byte ones ... */
1202 	inode->i_blocks = (i_size_read(inode) + 512 - 1) >> 9;
1203 	v9inode->cache_validity &= ~V9FS_INO_INVALID_ATTR;
1204 }
1205 
1206 /**
1207  * v9fs_qid2ino - convert qid into inode number
1208  * @qid: qid to hash
1209  *
1210  * BUG: potential for inode number collisions?
1211  */
1212 
1213 ino_t v9fs_qid2ino(struct p9_qid *qid)
1214 {
1215 	u64 path = qid->path + 2;
1216 	ino_t i = 0;
1217 
1218 	if (sizeof(ino_t) == sizeof(path))
1219 		memcpy(&i, &path, sizeof(ino_t));
1220 	else
1221 		i = (ino_t) (path ^ (path >> 32));
1222 
1223 	return i;
1224 }
1225 
1226 /**
1227  * v9fs_readlink - read a symlink's location (internal version)
1228  * @dentry: dentry for symlink
1229  * @buffer: buffer to load symlink location into
1230  * @buflen: length of buffer
1231  *
1232  */
1233 
1234 static int v9fs_readlink(struct dentry *dentry, char *buffer, int buflen)
1235 {
1236 	int retval;
1237 
1238 	struct v9fs_session_info *v9ses;
1239 	struct p9_fid *fid;
1240 	struct p9_wstat *st;
1241 
1242 	p9_debug(P9_DEBUG_VFS, " %s\n", dentry->d_name.name);
1243 	retval = -EPERM;
1244 	v9ses = v9fs_dentry2v9ses(dentry);
1245 	fid = v9fs_fid_lookup(dentry);
1246 	if (IS_ERR(fid))
1247 		return PTR_ERR(fid);
1248 
1249 	if (!v9fs_proto_dotu(v9ses))
1250 		return -EBADF;
1251 
1252 	st = p9_client_stat(fid);
1253 	if (IS_ERR(st))
1254 		return PTR_ERR(st);
1255 
1256 	if (!(st->mode & P9_DMSYMLINK)) {
1257 		retval = -EINVAL;
1258 		goto done;
1259 	}
1260 
1261 	/* copy extension buffer into buffer */
1262 	retval = min(strlen(st->extension)+1, (size_t)buflen);
1263 	memcpy(buffer, st->extension, retval);
1264 
1265 	p9_debug(P9_DEBUG_VFS, "%s -> %s (%.*s)\n",
1266 		 dentry->d_name.name, st->extension, buflen, buffer);
1267 
1268 done:
1269 	p9stat_free(st);
1270 	kfree(st);
1271 	return retval;
1272 }
1273 
1274 /**
1275  * v9fs_vfs_follow_link - follow a symlink path
1276  * @dentry: dentry for symlink
1277  * @nd: nameidata
1278  *
1279  */
1280 
1281 static void *v9fs_vfs_follow_link(struct dentry *dentry, struct nameidata *nd)
1282 {
1283 	int len = 0;
1284 	char *link = __getname();
1285 
1286 	p9_debug(P9_DEBUG_VFS, "%s\n", dentry->d_name.name);
1287 
1288 	if (!link)
1289 		link = ERR_PTR(-ENOMEM);
1290 	else {
1291 		len = v9fs_readlink(dentry, link, PATH_MAX);
1292 
1293 		if (len < 0) {
1294 			__putname(link);
1295 			link = ERR_PTR(len);
1296 		} else
1297 			link[min(len, PATH_MAX-1)] = 0;
1298 	}
1299 	nd_set_link(nd, link);
1300 
1301 	return NULL;
1302 }
1303 
1304 /**
1305  * v9fs_vfs_put_link - release a symlink path
1306  * @dentry: dentry for symlink
1307  * @nd: nameidata
1308  * @p: unused
1309  *
1310  */
1311 
1312 void
1313 v9fs_vfs_put_link(struct dentry *dentry, struct nameidata *nd, void *p)
1314 {
1315 	char *s = nd_get_link(nd);
1316 
1317 	p9_debug(P9_DEBUG_VFS, " %s %s\n",
1318 		 dentry->d_name.name, IS_ERR(s) ? "<error>" : s);
1319 	if (!IS_ERR(s))
1320 		__putname(s);
1321 }
1322 
1323 /**
1324  * v9fs_vfs_mkspecial - create a special file
1325  * @dir: inode to create special file in
1326  * @dentry: dentry to create
1327  * @mode: mode to create special file
1328  * @extension: 9p2000.u format extension string representing special file
1329  *
1330  */
1331 
1332 static int v9fs_vfs_mkspecial(struct inode *dir, struct dentry *dentry,
1333 	u32 perm, const char *extension)
1334 {
1335 	struct p9_fid *fid;
1336 	struct v9fs_session_info *v9ses;
1337 
1338 	v9ses = v9fs_inode2v9ses(dir);
1339 	if (!v9fs_proto_dotu(v9ses)) {
1340 		p9_debug(P9_DEBUG_ERROR, "not extended\n");
1341 		return -EPERM;
1342 	}
1343 
1344 	fid = v9fs_create(v9ses, dir, dentry, (char *) extension, perm,
1345 								P9_OREAD);
1346 	if (IS_ERR(fid))
1347 		return PTR_ERR(fid);
1348 
1349 	v9fs_invalidate_inode_attr(dir);
1350 	p9_client_clunk(fid);
1351 	return 0;
1352 }
1353 
1354 /**
1355  * v9fs_vfs_symlink - helper function to create symlinks
1356  * @dir: directory inode containing symlink
1357  * @dentry: dentry for symlink
1358  * @symname: symlink data
1359  *
1360  * See Also: 9P2000.u RFC for more information
1361  *
1362  */
1363 
1364 static int
1365 v9fs_vfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1366 {
1367 	p9_debug(P9_DEBUG_VFS, " %lu,%s,%s\n",
1368 		 dir->i_ino, dentry->d_name.name, symname);
1369 
1370 	return v9fs_vfs_mkspecial(dir, dentry, P9_DMSYMLINK, symname);
1371 }
1372 
1373 /**
1374  * v9fs_vfs_link - create a hardlink
1375  * @old_dentry: dentry for file to link to
1376  * @dir: inode destination for new link
1377  * @dentry: dentry for link
1378  *
1379  */
1380 
1381 static int
1382 v9fs_vfs_link(struct dentry *old_dentry, struct inode *dir,
1383 	      struct dentry *dentry)
1384 {
1385 	int retval;
1386 	char *name;
1387 	struct p9_fid *oldfid;
1388 
1389 	p9_debug(P9_DEBUG_VFS, " %lu,%s,%s\n",
1390 		 dir->i_ino, dentry->d_name.name, old_dentry->d_name.name);
1391 
1392 	oldfid = v9fs_fid_clone(old_dentry);
1393 	if (IS_ERR(oldfid))
1394 		return PTR_ERR(oldfid);
1395 
1396 	name = __getname();
1397 	if (unlikely(!name)) {
1398 		retval = -ENOMEM;
1399 		goto clunk_fid;
1400 	}
1401 
1402 	sprintf(name, "%d\n", oldfid->fid);
1403 	retval = v9fs_vfs_mkspecial(dir, dentry, P9_DMLINK, name);
1404 	__putname(name);
1405 	if (!retval) {
1406 		v9fs_refresh_inode(oldfid, old_dentry->d_inode);
1407 		v9fs_invalidate_inode_attr(dir);
1408 	}
1409 clunk_fid:
1410 	p9_client_clunk(oldfid);
1411 	return retval;
1412 }
1413 
1414 /**
1415  * v9fs_vfs_mknod - create a special file
1416  * @dir: inode destination for new link
1417  * @dentry: dentry for file
1418  * @mode: mode for creation
1419  * @rdev: device associated with special file
1420  *
1421  */
1422 
1423 static int
1424 v9fs_vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t rdev)
1425 {
1426 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
1427 	int retval;
1428 	char *name;
1429 	u32 perm;
1430 
1431 	p9_debug(P9_DEBUG_VFS, " %lu,%s mode: %hx MAJOR: %u MINOR: %u\n",
1432 		 dir->i_ino, dentry->d_name.name, mode,
1433 		 MAJOR(rdev), MINOR(rdev));
1434 
1435 	if (!new_valid_dev(rdev))
1436 		return -EINVAL;
1437 
1438 	name = __getname();
1439 	if (!name)
1440 		return -ENOMEM;
1441 	/* build extension */
1442 	if (S_ISBLK(mode))
1443 		sprintf(name, "b %u %u", MAJOR(rdev), MINOR(rdev));
1444 	else if (S_ISCHR(mode))
1445 		sprintf(name, "c %u %u", MAJOR(rdev), MINOR(rdev));
1446 	else if (S_ISFIFO(mode))
1447 		*name = 0;
1448 	else if (S_ISSOCK(mode))
1449 		*name = 0;
1450 	else {
1451 		__putname(name);
1452 		return -EINVAL;
1453 	}
1454 
1455 	perm = unixmode2p9mode(v9ses, mode);
1456 	retval = v9fs_vfs_mkspecial(dir, dentry, perm, name);
1457 	__putname(name);
1458 
1459 	return retval;
1460 }
1461 
1462 int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode)
1463 {
1464 	int umode;
1465 	dev_t rdev;
1466 	loff_t i_size;
1467 	struct p9_wstat *st;
1468 	struct v9fs_session_info *v9ses;
1469 
1470 	v9ses = v9fs_inode2v9ses(inode);
1471 	st = p9_client_stat(fid);
1472 	if (IS_ERR(st))
1473 		return PTR_ERR(st);
1474 	/*
1475 	 * Don't update inode if the file type is different
1476 	 */
1477 	umode = p9mode2unixmode(v9ses, st, &rdev);
1478 	if ((inode->i_mode & S_IFMT) != (umode & S_IFMT))
1479 		goto out;
1480 
1481 	spin_lock(&inode->i_lock);
1482 	/*
1483 	 * We don't want to refresh inode->i_size,
1484 	 * because we may have cached data
1485 	 */
1486 	i_size = inode->i_size;
1487 	v9fs_stat2inode(st, inode, inode->i_sb);
1488 	if (v9ses->cache)
1489 		inode->i_size = i_size;
1490 	spin_unlock(&inode->i_lock);
1491 out:
1492 	p9stat_free(st);
1493 	kfree(st);
1494 	return 0;
1495 }
1496 
1497 static const struct inode_operations v9fs_dir_inode_operations_dotu = {
1498 	.create = v9fs_vfs_create,
1499 	.lookup = v9fs_vfs_lookup,
1500 	.atomic_open = v9fs_vfs_atomic_open,
1501 	.symlink = v9fs_vfs_symlink,
1502 	.link = v9fs_vfs_link,
1503 	.unlink = v9fs_vfs_unlink,
1504 	.mkdir = v9fs_vfs_mkdir,
1505 	.rmdir = v9fs_vfs_rmdir,
1506 	.mknod = v9fs_vfs_mknod,
1507 	.rename = v9fs_vfs_rename,
1508 	.getattr = v9fs_vfs_getattr,
1509 	.setattr = v9fs_vfs_setattr,
1510 };
1511 
1512 static const struct inode_operations v9fs_dir_inode_operations = {
1513 	.create = v9fs_vfs_create,
1514 	.lookup = v9fs_vfs_lookup,
1515 	.atomic_open = v9fs_vfs_atomic_open,
1516 	.unlink = v9fs_vfs_unlink,
1517 	.mkdir = v9fs_vfs_mkdir,
1518 	.rmdir = v9fs_vfs_rmdir,
1519 	.mknod = v9fs_vfs_mknod,
1520 	.rename = v9fs_vfs_rename,
1521 	.getattr = v9fs_vfs_getattr,
1522 	.setattr = v9fs_vfs_setattr,
1523 };
1524 
1525 static const struct inode_operations v9fs_file_inode_operations = {
1526 	.getattr = v9fs_vfs_getattr,
1527 	.setattr = v9fs_vfs_setattr,
1528 };
1529 
1530 static const struct inode_operations v9fs_symlink_inode_operations = {
1531 	.readlink = generic_readlink,
1532 	.follow_link = v9fs_vfs_follow_link,
1533 	.put_link = v9fs_vfs_put_link,
1534 	.getattr = v9fs_vfs_getattr,
1535 	.setattr = v9fs_vfs_setattr,
1536 };
1537 
1538