xref: /openbmc/linux/fs/9p/vfs_inode.c (revision 47237687d73cbeae1dd7a133c3fc3d7239094568)
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 		strncpy(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 (uflags & O_TRUNC)
196 		ret |= P9_OTRUNC;
197 
198 	if (extended) {
199 		if (uflags & O_EXCL)
200 			ret |= P9_OEXCL;
201 
202 		if (uflags & O_APPEND)
203 			ret |= P9_OAPPEND;
204 	}
205 
206 	return ret;
207 }
208 
209 /**
210  * v9fs_blank_wstat - helper function to setup a 9P stat structure
211  * @wstat: structure to initialize
212  *
213  */
214 
215 void
216 v9fs_blank_wstat(struct p9_wstat *wstat)
217 {
218 	wstat->type = ~0;
219 	wstat->dev = ~0;
220 	wstat->qid.type = ~0;
221 	wstat->qid.version = ~0;
222 	*((long long *)&wstat->qid.path) = ~0;
223 	wstat->mode = ~0;
224 	wstat->atime = ~0;
225 	wstat->mtime = ~0;
226 	wstat->length = ~0;
227 	wstat->name = NULL;
228 	wstat->uid = NULL;
229 	wstat->gid = NULL;
230 	wstat->muid = NULL;
231 	wstat->n_uid = ~0;
232 	wstat->n_gid = ~0;
233 	wstat->n_muid = ~0;
234 	wstat->extension = NULL;
235 }
236 
237 /**
238  * v9fs_alloc_inode - helper function to allocate an inode
239  *
240  */
241 struct inode *v9fs_alloc_inode(struct super_block *sb)
242 {
243 	struct v9fs_inode *v9inode;
244 	v9inode = (struct v9fs_inode *)kmem_cache_alloc(v9fs_inode_cache,
245 							GFP_KERNEL);
246 	if (!v9inode)
247 		return NULL;
248 #ifdef CONFIG_9P_FSCACHE
249 	v9inode->fscache = NULL;
250 	spin_lock_init(&v9inode->fscache_lock);
251 #endif
252 	v9inode->writeback_fid = NULL;
253 	v9inode->cache_validity = 0;
254 	mutex_init(&v9inode->v_mutex);
255 	return &v9inode->vfs_inode;
256 }
257 
258 /**
259  * v9fs_destroy_inode - destroy an inode
260  *
261  */
262 
263 static void v9fs_i_callback(struct rcu_head *head)
264 {
265 	struct inode *inode = container_of(head, struct inode, i_rcu);
266 	kmem_cache_free(v9fs_inode_cache, V9FS_I(inode));
267 }
268 
269 void v9fs_destroy_inode(struct inode *inode)
270 {
271 	call_rcu(&inode->i_rcu, v9fs_i_callback);
272 }
273 
274 int v9fs_init_inode(struct v9fs_session_info *v9ses,
275 		    struct inode *inode, umode_t mode, dev_t rdev)
276 {
277 	int err = 0;
278 
279 	inode_init_owner(inode, NULL, mode);
280 	inode->i_blocks = 0;
281 	inode->i_rdev = rdev;
282 	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
283 	inode->i_mapping->a_ops = &v9fs_addr_operations;
284 
285 	switch (mode & S_IFMT) {
286 	case S_IFIFO:
287 	case S_IFBLK:
288 	case S_IFCHR:
289 	case S_IFSOCK:
290 		if (v9fs_proto_dotl(v9ses)) {
291 			inode->i_op = &v9fs_file_inode_operations_dotl;
292 		} else if (v9fs_proto_dotu(v9ses)) {
293 			inode->i_op = &v9fs_file_inode_operations;
294 		} else {
295 			p9_debug(P9_DEBUG_ERROR,
296 				 "special files without extended mode\n");
297 			err = -EINVAL;
298 			goto error;
299 		}
300 		init_special_inode(inode, inode->i_mode, inode->i_rdev);
301 		break;
302 	case S_IFREG:
303 		if (v9fs_proto_dotl(v9ses)) {
304 			inode->i_op = &v9fs_file_inode_operations_dotl;
305 			if (v9ses->cache)
306 				inode->i_fop =
307 					&v9fs_cached_file_operations_dotl;
308 			else
309 				inode->i_fop = &v9fs_file_operations_dotl;
310 		} else {
311 			inode->i_op = &v9fs_file_inode_operations;
312 			if (v9ses->cache)
313 				inode->i_fop = &v9fs_cached_file_operations;
314 			else
315 				inode->i_fop = &v9fs_file_operations;
316 		}
317 
318 		break;
319 	case S_IFLNK:
320 		if (!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)) {
321 			p9_debug(P9_DEBUG_ERROR,
322 				 "extended modes used with legacy protocol\n");
323 			err = -EINVAL;
324 			goto error;
325 		}
326 
327 		if (v9fs_proto_dotl(v9ses))
328 			inode->i_op = &v9fs_symlink_inode_operations_dotl;
329 		else
330 			inode->i_op = &v9fs_symlink_inode_operations;
331 
332 		break;
333 	case S_IFDIR:
334 		inc_nlink(inode);
335 		if (v9fs_proto_dotl(v9ses))
336 			inode->i_op = &v9fs_dir_inode_operations_dotl;
337 		else if (v9fs_proto_dotu(v9ses))
338 			inode->i_op = &v9fs_dir_inode_operations_dotu;
339 		else
340 			inode->i_op = &v9fs_dir_inode_operations;
341 
342 		if (v9fs_proto_dotl(v9ses))
343 			inode->i_fop = &v9fs_dir_operations_dotl;
344 		else
345 			inode->i_fop = &v9fs_dir_operations;
346 
347 		break;
348 	default:
349 		p9_debug(P9_DEBUG_ERROR, "BAD mode 0x%hx S_IFMT 0x%x\n",
350 			 mode, mode & S_IFMT);
351 		err = -EINVAL;
352 		goto error;
353 	}
354 error:
355 	return err;
356 
357 }
358 
359 /**
360  * v9fs_get_inode - helper function to setup an inode
361  * @sb: superblock
362  * @mode: mode to setup inode with
363  *
364  */
365 
366 struct inode *v9fs_get_inode(struct super_block *sb, umode_t mode, dev_t rdev)
367 {
368 	int err;
369 	struct inode *inode;
370 	struct v9fs_session_info *v9ses = sb->s_fs_info;
371 
372 	p9_debug(P9_DEBUG_VFS, "super block: %p mode: %ho\n", sb, mode);
373 
374 	inode = new_inode(sb);
375 	if (!inode) {
376 		pr_warn("%s (%d): Problem allocating inode\n",
377 			__func__, task_pid_nr(current));
378 		return ERR_PTR(-ENOMEM);
379 	}
380 	err = v9fs_init_inode(v9ses, inode, mode, rdev);
381 	if (err) {
382 		iput(inode);
383 		return ERR_PTR(err);
384 	}
385 	return inode;
386 }
387 
388 /*
389 static struct v9fs_fid*
390 v9fs_clone_walk(struct v9fs_session_info *v9ses, u32 fid, struct dentry *dentry)
391 {
392 	int err;
393 	int nfid;
394 	struct v9fs_fid *ret;
395 	struct v9fs_fcall *fcall;
396 
397 	nfid = v9fs_get_idpool(&v9ses->fidpool);
398 	if (nfid < 0) {
399 		eprintk(KERN_WARNING, "no free fids available\n");
400 		return ERR_PTR(-ENOSPC);
401 	}
402 
403 	err = v9fs_t_walk(v9ses, fid, nfid, (char *) dentry->d_name.name,
404 		&fcall);
405 
406 	if (err < 0) {
407 		if (fcall && fcall->id == RWALK)
408 			goto clunk_fid;
409 
410 		PRINT_FCALL_ERROR("walk error", fcall);
411 		v9fs_put_idpool(nfid, &v9ses->fidpool);
412 		goto error;
413 	}
414 
415 	kfree(fcall);
416 	fcall = NULL;
417 	ret = v9fs_fid_create(v9ses, nfid);
418 	if (!ret) {
419 		err = -ENOMEM;
420 		goto clunk_fid;
421 	}
422 
423 	err = v9fs_fid_insert(ret, dentry);
424 	if (err < 0) {
425 		v9fs_fid_destroy(ret);
426 		goto clunk_fid;
427 	}
428 
429 	return ret;
430 
431 clunk_fid:
432 	v9fs_t_clunk(v9ses, nfid);
433 
434 error:
435 	kfree(fcall);
436 	return ERR_PTR(err);
437 }
438 */
439 
440 
441 /**
442  * v9fs_clear_inode - release an inode
443  * @inode: inode to release
444  *
445  */
446 void v9fs_evict_inode(struct inode *inode)
447 {
448 	struct v9fs_inode *v9inode = V9FS_I(inode);
449 
450 	truncate_inode_pages(inode->i_mapping, 0);
451 	clear_inode(inode);
452 	filemap_fdatawrite(inode->i_mapping);
453 
454 #ifdef CONFIG_9P_FSCACHE
455 	v9fs_cache_inode_put_cookie(inode);
456 #endif
457 	/* clunk the fid stashed in writeback_fid */
458 	if (v9inode->writeback_fid) {
459 		p9_client_clunk(v9inode->writeback_fid);
460 		v9inode->writeback_fid = NULL;
461 	}
462 }
463 
464 static int v9fs_test_inode(struct inode *inode, void *data)
465 {
466 	int umode;
467 	dev_t rdev;
468 	struct v9fs_inode *v9inode = V9FS_I(inode);
469 	struct p9_wstat *st = (struct p9_wstat *)data;
470 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
471 
472 	umode = p9mode2unixmode(v9ses, st, &rdev);
473 	/* don't match inode of different type */
474 	if ((inode->i_mode & S_IFMT) != (umode & S_IFMT))
475 		return 0;
476 
477 	/* compare qid details */
478 	if (memcmp(&v9inode->qid.version,
479 		   &st->qid.version, sizeof(v9inode->qid.version)))
480 		return 0;
481 
482 	if (v9inode->qid.type != st->qid.type)
483 		return 0;
484 	return 1;
485 }
486 
487 static int v9fs_test_new_inode(struct inode *inode, void *data)
488 {
489 	return 0;
490 }
491 
492 static int v9fs_set_inode(struct inode *inode,  void *data)
493 {
494 	struct v9fs_inode *v9inode = V9FS_I(inode);
495 	struct p9_wstat *st = (struct p9_wstat *)data;
496 
497 	memcpy(&v9inode->qid, &st->qid, sizeof(st->qid));
498 	return 0;
499 }
500 
501 static struct inode *v9fs_qid_iget(struct super_block *sb,
502 				   struct p9_qid *qid,
503 				   struct p9_wstat *st,
504 				   int new)
505 {
506 	dev_t rdev;
507 	int retval;
508 	umode_t umode;
509 	unsigned long i_ino;
510 	struct inode *inode;
511 	struct v9fs_session_info *v9ses = sb->s_fs_info;
512 	int (*test)(struct inode *, void *);
513 
514 	if (new)
515 		test = v9fs_test_new_inode;
516 	else
517 		test = v9fs_test_inode;
518 
519 	i_ino = v9fs_qid2ino(qid);
520 	inode = iget5_locked(sb, i_ino, test, v9fs_set_inode, st);
521 	if (!inode)
522 		return ERR_PTR(-ENOMEM);
523 	if (!(inode->i_state & I_NEW))
524 		return inode;
525 	/*
526 	 * initialize the inode with the stat info
527 	 * FIXME!! we may need support for stale inodes
528 	 * later.
529 	 */
530 	inode->i_ino = i_ino;
531 	umode = p9mode2unixmode(v9ses, st, &rdev);
532 	retval = v9fs_init_inode(v9ses, inode, umode, rdev);
533 	if (retval)
534 		goto error;
535 
536 	v9fs_stat2inode(st, inode, sb);
537 #ifdef CONFIG_9P_FSCACHE
538 	v9fs_cache_inode_get_cookie(inode);
539 #endif
540 	unlock_new_inode(inode);
541 	return inode;
542 error:
543 	unlock_new_inode(inode);
544 	iput(inode);
545 	return ERR_PTR(retval);
546 
547 }
548 
549 struct inode *
550 v9fs_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
551 		    struct super_block *sb, int new)
552 {
553 	struct p9_wstat *st;
554 	struct inode *inode = NULL;
555 
556 	st = p9_client_stat(fid);
557 	if (IS_ERR(st))
558 		return ERR_CAST(st);
559 
560 	inode = v9fs_qid_iget(sb, &st->qid, st, new);
561 	p9stat_free(st);
562 	kfree(st);
563 	return inode;
564 }
565 
566 /**
567  * v9fs_at_to_dotl_flags- convert Linux specific AT flags to
568  * plan 9 AT flag.
569  * @flags: flags to convert
570  */
571 static int v9fs_at_to_dotl_flags(int flags)
572 {
573 	int rflags = 0;
574 	if (flags & AT_REMOVEDIR)
575 		rflags |= P9_DOTL_AT_REMOVEDIR;
576 	return rflags;
577 }
578 
579 /**
580  * v9fs_remove - helper function to remove files and directories
581  * @dir: directory inode that is being deleted
582  * @dentry:  dentry that is being deleted
583  * @rmdir: removing a directory
584  *
585  */
586 
587 static int v9fs_remove(struct inode *dir, struct dentry *dentry, int flags)
588 {
589 	struct inode *inode;
590 	int retval = -EOPNOTSUPP;
591 	struct p9_fid *v9fid, *dfid;
592 	struct v9fs_session_info *v9ses;
593 
594 	p9_debug(P9_DEBUG_VFS, "inode: %p dentry: %p rmdir: %x\n",
595 		 dir, dentry, flags);
596 
597 	v9ses = v9fs_inode2v9ses(dir);
598 	inode = dentry->d_inode;
599 	dfid = v9fs_fid_lookup(dentry->d_parent);
600 	if (IS_ERR(dfid)) {
601 		retval = PTR_ERR(dfid);
602 		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", retval);
603 		return retval;
604 	}
605 	if (v9fs_proto_dotl(v9ses))
606 		retval = p9_client_unlinkat(dfid, dentry->d_name.name,
607 					    v9fs_at_to_dotl_flags(flags));
608 	if (retval == -EOPNOTSUPP) {
609 		/* Try the one based on path */
610 		v9fid = v9fs_fid_clone(dentry);
611 		if (IS_ERR(v9fid))
612 			return PTR_ERR(v9fid);
613 		retval = p9_client_remove(v9fid);
614 	}
615 	if (!retval) {
616 		/*
617 		 * directories on unlink should have zero
618 		 * link count
619 		 */
620 		if (flags & AT_REMOVEDIR) {
621 			clear_nlink(inode);
622 			drop_nlink(dir);
623 		} else
624 			drop_nlink(inode);
625 
626 		v9fs_invalidate_inode_attr(inode);
627 		v9fs_invalidate_inode_attr(dir);
628 	}
629 	return retval;
630 }
631 
632 /**
633  * v9fs_create - Create a file
634  * @v9ses: session information
635  * @dir: directory that dentry is being created in
636  * @dentry:  dentry that is being created
637  * @extension: 9p2000.u extension string to support devices, etc.
638  * @perm: create permissions
639  * @mode: open mode
640  *
641  */
642 static struct p9_fid *
643 v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
644 		struct dentry *dentry, char *extension, u32 perm, u8 mode)
645 {
646 	int err;
647 	char *name;
648 	struct p9_fid *dfid, *ofid, *fid;
649 	struct inode *inode;
650 
651 	p9_debug(P9_DEBUG_VFS, "name %s\n", dentry->d_name.name);
652 
653 	err = 0;
654 	ofid = NULL;
655 	fid = NULL;
656 	name = (char *) dentry->d_name.name;
657 	dfid = v9fs_fid_lookup(dentry->d_parent);
658 	if (IS_ERR(dfid)) {
659 		err = PTR_ERR(dfid);
660 		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", err);
661 		return ERR_PTR(err);
662 	}
663 
664 	/* clone a fid to use for creation */
665 	ofid = p9_client_walk(dfid, 0, NULL, 1);
666 	if (IS_ERR(ofid)) {
667 		err = PTR_ERR(ofid);
668 		p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n", err);
669 		return ERR_PTR(err);
670 	}
671 
672 	err = p9_client_fcreate(ofid, name, perm, mode, extension);
673 	if (err < 0) {
674 		p9_debug(P9_DEBUG_VFS, "p9_client_fcreate failed %d\n", err);
675 		goto error;
676 	}
677 
678 	if (!(perm & P9_DMLINK)) {
679 		/* now walk from the parent so we can get unopened fid */
680 		fid = p9_client_walk(dfid, 1, &name, 1);
681 		if (IS_ERR(fid)) {
682 			err = PTR_ERR(fid);
683 			p9_debug(P9_DEBUG_VFS,
684 				   "p9_client_walk failed %d\n", err);
685 			fid = NULL;
686 			goto error;
687 		}
688 		/*
689 		 * instantiate inode and assign the unopened fid to the dentry
690 		 */
691 		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
692 		if (IS_ERR(inode)) {
693 			err = PTR_ERR(inode);
694 			p9_debug(P9_DEBUG_VFS,
695 				   "inode creation failed %d\n", err);
696 			goto error;
697 		}
698 		err = v9fs_fid_add(dentry, fid);
699 		if (err < 0)
700 			goto error;
701 		d_instantiate(dentry, inode);
702 	}
703 	return ofid;
704 error:
705 	if (ofid)
706 		p9_client_clunk(ofid);
707 
708 	if (fid)
709 		p9_client_clunk(fid);
710 
711 	return ERR_PTR(err);
712 }
713 
714 /**
715  * v9fs_vfs_create - VFS hook to create a regular file
716  *
717  * open(.., O_CREAT) is handled in v9fs_vfs_atomic_open().  This is only called
718  * for mknod(2).
719  *
720  * @dir: directory inode that is being created
721  * @dentry:  dentry that is being deleted
722  * @mode: create permissions
723  *
724  */
725 
726 static int
727 v9fs_vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
728 		struct nameidata *nd)
729 {
730 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
731 	u32 perm = unixmode2p9mode(v9ses, mode);
732 	struct p9_fid *fid;
733 
734 	/* P9_OEXCL? */
735 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_ORDWR);
736 	if (IS_ERR(fid))
737 		return PTR_ERR(fid);
738 
739 	v9fs_invalidate_inode_attr(dir);
740 	p9_client_clunk(fid);
741 
742 	return 0;
743 }
744 
745 /**
746  * v9fs_vfs_mkdir - VFS mkdir hook to create a directory
747  * @dir:  inode that is being unlinked
748  * @dentry: dentry that is being unlinked
749  * @mode: mode for new directory
750  *
751  */
752 
753 static int v9fs_vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
754 {
755 	int err;
756 	u32 perm;
757 	struct p9_fid *fid;
758 	struct v9fs_session_info *v9ses;
759 
760 	p9_debug(P9_DEBUG_VFS, "name %s\n", dentry->d_name.name);
761 	err = 0;
762 	v9ses = v9fs_inode2v9ses(dir);
763 	perm = unixmode2p9mode(v9ses, mode | S_IFDIR);
764 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_OREAD);
765 	if (IS_ERR(fid)) {
766 		err = PTR_ERR(fid);
767 		fid = NULL;
768 	} else {
769 		inc_nlink(dir);
770 		v9fs_invalidate_inode_attr(dir);
771 	}
772 
773 	if (fid)
774 		p9_client_clunk(fid);
775 
776 	return err;
777 }
778 
779 /**
780  * v9fs_vfs_lookup - VFS lookup hook to "walk" to a new inode
781  * @dir:  inode that is being walked from
782  * @dentry: dentry that is being walked to?
783  * @nameidata: path data
784  *
785  */
786 
787 struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
788 				      struct nameidata *nameidata)
789 {
790 	struct dentry *res;
791 	struct super_block *sb;
792 	struct v9fs_session_info *v9ses;
793 	struct p9_fid *dfid, *fid;
794 	struct inode *inode;
795 	char *name;
796 	int result = 0;
797 
798 	p9_debug(P9_DEBUG_VFS, "dir: %p dentry: (%s) %p nameidata: %p\n",
799 		 dir, dentry->d_name.name, dentry, nameidata);
800 
801 	if (dentry->d_name.len > NAME_MAX)
802 		return ERR_PTR(-ENAMETOOLONG);
803 
804 	sb = dir->i_sb;
805 	v9ses = v9fs_inode2v9ses(dir);
806 	/* We can walk d_parent because we hold the dir->i_mutex */
807 	dfid = v9fs_fid_lookup(dentry->d_parent);
808 	if (IS_ERR(dfid))
809 		return ERR_CAST(dfid);
810 
811 	name = (char *) dentry->d_name.name;
812 	fid = p9_client_walk(dfid, 1, &name, 1);
813 	if (IS_ERR(fid)) {
814 		result = PTR_ERR(fid);
815 		if (result == -ENOENT) {
816 			inode = NULL;
817 			goto inst_out;
818 		}
819 
820 		return ERR_PTR(result);
821 	}
822 	/*
823 	 * Make sure we don't use a wrong inode due to parallel
824 	 * unlink. For cached mode create calls request for new
825 	 * inode. But with cache disabled, lookup should do this.
826 	 */
827 	if (v9ses->cache)
828 		inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
829 	else
830 		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
831 	if (IS_ERR(inode)) {
832 		result = PTR_ERR(inode);
833 		inode = NULL;
834 		goto error;
835 	}
836 	result = v9fs_fid_add(dentry, fid);
837 	if (result < 0)
838 		goto error_iput;
839 inst_out:
840 	/*
841 	 * If we had a rename on the server and a parallel lookup
842 	 * for the new name, then make sure we instantiate with
843 	 * the new name. ie look up for a/b, while on server somebody
844 	 * moved b under k and client parallely did a lookup for
845 	 * k/b.
846 	 */
847 	res = d_materialise_unique(dentry, inode);
848 	if (!IS_ERR(res))
849 		return res;
850 	result = PTR_ERR(res);
851 error_iput:
852 	iput(inode);
853 error:
854 	p9_client_clunk(fid);
855 
856 	return ERR_PTR(result);
857 }
858 
859 static struct file *
860 v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
861 		     struct opendata *od, unsigned flags, umode_t mode,
862 		     int *opened)
863 {
864 	int err;
865 	u32 perm;
866 	struct file *filp;
867 	struct v9fs_inode *v9inode;
868 	struct v9fs_session_info *v9ses;
869 	struct p9_fid *fid, *inode_fid;
870 	struct dentry *res = NULL;
871 
872 	if (d_unhashed(dentry)) {
873 		res = v9fs_vfs_lookup(dir, dentry, NULL);
874 		if (IS_ERR(res))
875 			return ERR_CAST(res);
876 
877 		if (res)
878 			dentry = res;
879 	}
880 
881 	/* Only creates */
882 	if (!(flags & O_CREAT) || dentry->d_inode) {
883 		finish_no_open(od, res);
884 		return NULL;
885 	}
886 
887 	err = 0;
888 	fid = NULL;
889 	v9ses = v9fs_inode2v9ses(dir);
890 	perm = unixmode2p9mode(v9ses, mode);
891 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm,
892 				v9fs_uflags2omode(flags,
893 						v9fs_proto_dotu(v9ses)));
894 	if (IS_ERR(fid)) {
895 		err = PTR_ERR(fid);
896 		fid = NULL;
897 		goto error;
898 	}
899 
900 	v9fs_invalidate_inode_attr(dir);
901 	v9inode = V9FS_I(dentry->d_inode);
902 	mutex_lock(&v9inode->v_mutex);
903 	if (v9ses->cache && !v9inode->writeback_fid &&
904 	    ((flags & O_ACCMODE) != O_RDONLY)) {
905 		/*
906 		 * clone a fid and add it to writeback_fid
907 		 * we do it during open time instead of
908 		 * page dirty time via write_begin/page_mkwrite
909 		 * because we want write after unlink usecase
910 		 * to work.
911 		 */
912 		inode_fid = v9fs_writeback_fid(dentry);
913 		if (IS_ERR(inode_fid)) {
914 			err = PTR_ERR(inode_fid);
915 			mutex_unlock(&v9inode->v_mutex);
916 			goto error;
917 		}
918 		v9inode->writeback_fid = (void *) inode_fid;
919 	}
920 	mutex_unlock(&v9inode->v_mutex);
921 	filp = finish_open(od, dentry, generic_file_open, opened);
922 	if (IS_ERR(filp)) {
923 		err = PTR_ERR(filp);
924 		goto error;
925 	}
926 
927 	filp->private_data = fid;
928 #ifdef CONFIG_9P_FSCACHE
929 	if (v9ses->cache)
930 		v9fs_cache_inode_set_cookie(dentry->d_inode, filp);
931 #endif
932 
933 	*opened |= FILE_CREATED;
934 out:
935 	dput(res);
936 	return filp;
937 
938 error:
939 	if (fid)
940 		p9_client_clunk(fid);
941 
942 	filp = ERR_PTR(err);
943 	goto out;
944 }
945 
946 /**
947  * v9fs_vfs_unlink - VFS unlink hook to delete an inode
948  * @i:  inode that is being unlinked
949  * @d: dentry that is being unlinked
950  *
951  */
952 
953 int v9fs_vfs_unlink(struct inode *i, struct dentry *d)
954 {
955 	return v9fs_remove(i, d, 0);
956 }
957 
958 /**
959  * v9fs_vfs_rmdir - VFS unlink hook to delete a directory
960  * @i:  inode that is being unlinked
961  * @d: dentry that is being unlinked
962  *
963  */
964 
965 int v9fs_vfs_rmdir(struct inode *i, struct dentry *d)
966 {
967 	return v9fs_remove(i, d, AT_REMOVEDIR);
968 }
969 
970 /**
971  * v9fs_vfs_rename - VFS hook to rename an inode
972  * @old_dir:  old dir inode
973  * @old_dentry: old dentry
974  * @new_dir: new dir inode
975  * @new_dentry: new dentry
976  *
977  */
978 
979 int
980 v9fs_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
981 		struct inode *new_dir, struct dentry *new_dentry)
982 {
983 	int retval;
984 	struct inode *old_inode;
985 	struct inode *new_inode;
986 	struct v9fs_session_info *v9ses;
987 	struct p9_fid *oldfid;
988 	struct p9_fid *olddirfid;
989 	struct p9_fid *newdirfid;
990 	struct p9_wstat wstat;
991 
992 	p9_debug(P9_DEBUG_VFS, "\n");
993 	retval = 0;
994 	old_inode = old_dentry->d_inode;
995 	new_inode = new_dentry->d_inode;
996 	v9ses = v9fs_inode2v9ses(old_inode);
997 	oldfid = v9fs_fid_lookup(old_dentry);
998 	if (IS_ERR(oldfid))
999 		return PTR_ERR(oldfid);
1000 
1001 	olddirfid = v9fs_fid_clone(old_dentry->d_parent);
1002 	if (IS_ERR(olddirfid)) {
1003 		retval = PTR_ERR(olddirfid);
1004 		goto done;
1005 	}
1006 
1007 	newdirfid = v9fs_fid_clone(new_dentry->d_parent);
1008 	if (IS_ERR(newdirfid)) {
1009 		retval = PTR_ERR(newdirfid);
1010 		goto clunk_olddir;
1011 	}
1012 
1013 	down_write(&v9ses->rename_sem);
1014 	if (v9fs_proto_dotl(v9ses)) {
1015 		retval = p9_client_renameat(olddirfid, old_dentry->d_name.name,
1016 					    newdirfid, new_dentry->d_name.name);
1017 		if (retval == -EOPNOTSUPP)
1018 			retval = p9_client_rename(oldfid, newdirfid,
1019 						  new_dentry->d_name.name);
1020 		if (retval != -EOPNOTSUPP)
1021 			goto clunk_newdir;
1022 	}
1023 	if (old_dentry->d_parent != new_dentry->d_parent) {
1024 		/*
1025 		 * 9P .u can only handle file rename in the same directory
1026 		 */
1027 
1028 		p9_debug(P9_DEBUG_ERROR, "old dir and new dir are different\n");
1029 		retval = -EXDEV;
1030 		goto clunk_newdir;
1031 	}
1032 	v9fs_blank_wstat(&wstat);
1033 	wstat.muid = v9ses->uname;
1034 	wstat.name = (char *) new_dentry->d_name.name;
1035 	retval = p9_client_wstat(oldfid, &wstat);
1036 
1037 clunk_newdir:
1038 	if (!retval) {
1039 		if (new_inode) {
1040 			if (S_ISDIR(new_inode->i_mode))
1041 				clear_nlink(new_inode);
1042 			else
1043 				drop_nlink(new_inode);
1044 		}
1045 		if (S_ISDIR(old_inode->i_mode)) {
1046 			if (!new_inode)
1047 				inc_nlink(new_dir);
1048 			drop_nlink(old_dir);
1049 		}
1050 		v9fs_invalidate_inode_attr(old_inode);
1051 		v9fs_invalidate_inode_attr(old_dir);
1052 		v9fs_invalidate_inode_attr(new_dir);
1053 
1054 		/* successful rename */
1055 		d_move(old_dentry, new_dentry);
1056 	}
1057 	up_write(&v9ses->rename_sem);
1058 	p9_client_clunk(newdirfid);
1059 
1060 clunk_olddir:
1061 	p9_client_clunk(olddirfid);
1062 
1063 done:
1064 	return retval;
1065 }
1066 
1067 /**
1068  * v9fs_vfs_getattr - retrieve file metadata
1069  * @mnt: mount information
1070  * @dentry: file to get attributes on
1071  * @stat: metadata structure to populate
1072  *
1073  */
1074 
1075 static int
1076 v9fs_vfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
1077 		 struct kstat *stat)
1078 {
1079 	int err;
1080 	struct v9fs_session_info *v9ses;
1081 	struct p9_fid *fid;
1082 	struct p9_wstat *st;
1083 
1084 	p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
1085 	err = -EPERM;
1086 	v9ses = v9fs_dentry2v9ses(dentry);
1087 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
1088 		generic_fillattr(dentry->d_inode, stat);
1089 		return 0;
1090 	}
1091 	fid = v9fs_fid_lookup(dentry);
1092 	if (IS_ERR(fid))
1093 		return PTR_ERR(fid);
1094 
1095 	st = p9_client_stat(fid);
1096 	if (IS_ERR(st))
1097 		return PTR_ERR(st);
1098 
1099 	v9fs_stat2inode(st, dentry->d_inode, dentry->d_inode->i_sb);
1100 	generic_fillattr(dentry->d_inode, stat);
1101 
1102 	p9stat_free(st);
1103 	kfree(st);
1104 	return 0;
1105 }
1106 
1107 /**
1108  * v9fs_vfs_setattr - set file metadata
1109  * @dentry: file whose metadata to set
1110  * @iattr: metadata assignment structure
1111  *
1112  */
1113 
1114 static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
1115 {
1116 	int retval;
1117 	struct v9fs_session_info *v9ses;
1118 	struct p9_fid *fid;
1119 	struct p9_wstat wstat;
1120 
1121 	p9_debug(P9_DEBUG_VFS, "\n");
1122 	retval = inode_change_ok(dentry->d_inode, iattr);
1123 	if (retval)
1124 		return retval;
1125 
1126 	retval = -EPERM;
1127 	v9ses = v9fs_dentry2v9ses(dentry);
1128 	fid = v9fs_fid_lookup(dentry);
1129 	if(IS_ERR(fid))
1130 		return PTR_ERR(fid);
1131 
1132 	v9fs_blank_wstat(&wstat);
1133 	if (iattr->ia_valid & ATTR_MODE)
1134 		wstat.mode = unixmode2p9mode(v9ses, iattr->ia_mode);
1135 
1136 	if (iattr->ia_valid & ATTR_MTIME)
1137 		wstat.mtime = iattr->ia_mtime.tv_sec;
1138 
1139 	if (iattr->ia_valid & ATTR_ATIME)
1140 		wstat.atime = iattr->ia_atime.tv_sec;
1141 
1142 	if (iattr->ia_valid & ATTR_SIZE)
1143 		wstat.length = iattr->ia_size;
1144 
1145 	if (v9fs_proto_dotu(v9ses)) {
1146 		if (iattr->ia_valid & ATTR_UID)
1147 			wstat.n_uid = iattr->ia_uid;
1148 
1149 		if (iattr->ia_valid & ATTR_GID)
1150 			wstat.n_gid = iattr->ia_gid;
1151 	}
1152 
1153 	/* Write all dirty data */
1154 	if (S_ISREG(dentry->d_inode->i_mode))
1155 		filemap_write_and_wait(dentry->d_inode->i_mapping);
1156 
1157 	retval = p9_client_wstat(fid, &wstat);
1158 	if (retval < 0)
1159 		return retval;
1160 
1161 	if ((iattr->ia_valid & ATTR_SIZE) &&
1162 	    iattr->ia_size != i_size_read(dentry->d_inode))
1163 		truncate_setsize(dentry->d_inode, iattr->ia_size);
1164 
1165 	v9fs_invalidate_inode_attr(dentry->d_inode);
1166 
1167 	setattr_copy(dentry->d_inode, iattr);
1168 	mark_inode_dirty(dentry->d_inode);
1169 	return 0;
1170 }
1171 
1172 /**
1173  * v9fs_stat2inode - populate an inode structure with mistat info
1174  * @stat: Plan 9 metadata (mistat) structure
1175  * @inode: inode to populate
1176  * @sb: superblock of filesystem
1177  *
1178  */
1179 
1180 void
1181 v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
1182 	struct super_block *sb)
1183 {
1184 	umode_t mode;
1185 	char ext[32];
1186 	char tag_name[14];
1187 	unsigned int i_nlink;
1188 	struct v9fs_session_info *v9ses = sb->s_fs_info;
1189 	struct v9fs_inode *v9inode = V9FS_I(inode);
1190 
1191 	set_nlink(inode, 1);
1192 
1193 	inode->i_atime.tv_sec = stat->atime;
1194 	inode->i_mtime.tv_sec = stat->mtime;
1195 	inode->i_ctime.tv_sec = stat->mtime;
1196 
1197 	inode->i_uid = v9ses->dfltuid;
1198 	inode->i_gid = v9ses->dfltgid;
1199 
1200 	if (v9fs_proto_dotu(v9ses)) {
1201 		inode->i_uid = stat->n_uid;
1202 		inode->i_gid = stat->n_gid;
1203 	}
1204 	if ((S_ISREG(inode->i_mode)) || (S_ISDIR(inode->i_mode))) {
1205 		if (v9fs_proto_dotu(v9ses) && (stat->extension[0] != '\0')) {
1206 			/*
1207 			 * Hadlink support got added later to
1208 			 * to the .u extension. So there can be
1209 			 * server out there that doesn't support
1210 			 * this even with .u extension. So check
1211 			 * for non NULL stat->extension
1212 			 */
1213 			strncpy(ext, stat->extension, sizeof(ext));
1214 			/* HARDLINKCOUNT %u */
1215 			sscanf(ext, "%13s %u", tag_name, &i_nlink);
1216 			if (!strncmp(tag_name, "HARDLINKCOUNT", 13))
1217 				set_nlink(inode, i_nlink);
1218 		}
1219 	}
1220 	mode = p9mode2perm(v9ses, stat);
1221 	mode |= inode->i_mode & ~S_IALLUGO;
1222 	inode->i_mode = mode;
1223 	i_size_write(inode, stat->length);
1224 
1225 	/* not real number of blocks, but 512 byte ones ... */
1226 	inode->i_blocks = (i_size_read(inode) + 512 - 1) >> 9;
1227 	v9inode->cache_validity &= ~V9FS_INO_INVALID_ATTR;
1228 }
1229 
1230 /**
1231  * v9fs_qid2ino - convert qid into inode number
1232  * @qid: qid to hash
1233  *
1234  * BUG: potential for inode number collisions?
1235  */
1236 
1237 ino_t v9fs_qid2ino(struct p9_qid *qid)
1238 {
1239 	u64 path = qid->path + 2;
1240 	ino_t i = 0;
1241 
1242 	if (sizeof(ino_t) == sizeof(path))
1243 		memcpy(&i, &path, sizeof(ino_t));
1244 	else
1245 		i = (ino_t) (path ^ (path >> 32));
1246 
1247 	return i;
1248 }
1249 
1250 /**
1251  * v9fs_readlink - read a symlink's location (internal version)
1252  * @dentry: dentry for symlink
1253  * @buffer: buffer to load symlink location into
1254  * @buflen: length of buffer
1255  *
1256  */
1257 
1258 static int v9fs_readlink(struct dentry *dentry, char *buffer, int buflen)
1259 {
1260 	int retval;
1261 
1262 	struct v9fs_session_info *v9ses;
1263 	struct p9_fid *fid;
1264 	struct p9_wstat *st;
1265 
1266 	p9_debug(P9_DEBUG_VFS, " %s\n", dentry->d_name.name);
1267 	retval = -EPERM;
1268 	v9ses = v9fs_dentry2v9ses(dentry);
1269 	fid = v9fs_fid_lookup(dentry);
1270 	if (IS_ERR(fid))
1271 		return PTR_ERR(fid);
1272 
1273 	if (!v9fs_proto_dotu(v9ses))
1274 		return -EBADF;
1275 
1276 	st = p9_client_stat(fid);
1277 	if (IS_ERR(st))
1278 		return PTR_ERR(st);
1279 
1280 	if (!(st->mode & P9_DMSYMLINK)) {
1281 		retval = -EINVAL;
1282 		goto done;
1283 	}
1284 
1285 	/* copy extension buffer into buffer */
1286 	strncpy(buffer, st->extension, buflen);
1287 
1288 	p9_debug(P9_DEBUG_VFS, "%s -> %s (%s)\n",
1289 		 dentry->d_name.name, st->extension, buffer);
1290 
1291 	retval = strnlen(buffer, buflen);
1292 done:
1293 	p9stat_free(st);
1294 	kfree(st);
1295 	return retval;
1296 }
1297 
1298 /**
1299  * v9fs_vfs_follow_link - follow a symlink path
1300  * @dentry: dentry for symlink
1301  * @nd: nameidata
1302  *
1303  */
1304 
1305 static void *v9fs_vfs_follow_link(struct dentry *dentry, struct nameidata *nd)
1306 {
1307 	int len = 0;
1308 	char *link = __getname();
1309 
1310 	p9_debug(P9_DEBUG_VFS, "%s\n", dentry->d_name.name);
1311 
1312 	if (!link)
1313 		link = ERR_PTR(-ENOMEM);
1314 	else {
1315 		len = v9fs_readlink(dentry, link, PATH_MAX);
1316 
1317 		if (len < 0) {
1318 			__putname(link);
1319 			link = ERR_PTR(len);
1320 		} else
1321 			link[min(len, PATH_MAX-1)] = 0;
1322 	}
1323 	nd_set_link(nd, link);
1324 
1325 	return NULL;
1326 }
1327 
1328 /**
1329  * v9fs_vfs_put_link - release a symlink path
1330  * @dentry: dentry for symlink
1331  * @nd: nameidata
1332  * @p: unused
1333  *
1334  */
1335 
1336 void
1337 v9fs_vfs_put_link(struct dentry *dentry, struct nameidata *nd, void *p)
1338 {
1339 	char *s = nd_get_link(nd);
1340 
1341 	p9_debug(P9_DEBUG_VFS, " %s %s\n",
1342 		 dentry->d_name.name, IS_ERR(s) ? "<error>" : s);
1343 	if (!IS_ERR(s))
1344 		__putname(s);
1345 }
1346 
1347 /**
1348  * v9fs_vfs_mkspecial - create a special file
1349  * @dir: inode to create special file in
1350  * @dentry: dentry to create
1351  * @mode: mode to create special file
1352  * @extension: 9p2000.u format extension string representing special file
1353  *
1354  */
1355 
1356 static int v9fs_vfs_mkspecial(struct inode *dir, struct dentry *dentry,
1357 	u32 perm, const char *extension)
1358 {
1359 	struct p9_fid *fid;
1360 	struct v9fs_session_info *v9ses;
1361 
1362 	v9ses = v9fs_inode2v9ses(dir);
1363 	if (!v9fs_proto_dotu(v9ses)) {
1364 		p9_debug(P9_DEBUG_ERROR, "not extended\n");
1365 		return -EPERM;
1366 	}
1367 
1368 	fid = v9fs_create(v9ses, dir, dentry, (char *) extension, perm,
1369 								P9_OREAD);
1370 	if (IS_ERR(fid))
1371 		return PTR_ERR(fid);
1372 
1373 	v9fs_invalidate_inode_attr(dir);
1374 	p9_client_clunk(fid);
1375 	return 0;
1376 }
1377 
1378 /**
1379  * v9fs_vfs_symlink - helper function to create symlinks
1380  * @dir: directory inode containing symlink
1381  * @dentry: dentry for symlink
1382  * @symname: symlink data
1383  *
1384  * See Also: 9P2000.u RFC for more information
1385  *
1386  */
1387 
1388 static int
1389 v9fs_vfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1390 {
1391 	p9_debug(P9_DEBUG_VFS, " %lu,%s,%s\n",
1392 		 dir->i_ino, dentry->d_name.name, symname);
1393 
1394 	return v9fs_vfs_mkspecial(dir, dentry, P9_DMSYMLINK, symname);
1395 }
1396 
1397 /**
1398  * v9fs_vfs_link - create a hardlink
1399  * @old_dentry: dentry for file to link to
1400  * @dir: inode destination for new link
1401  * @dentry: dentry for link
1402  *
1403  */
1404 
1405 static int
1406 v9fs_vfs_link(struct dentry *old_dentry, struct inode *dir,
1407 	      struct dentry *dentry)
1408 {
1409 	int retval;
1410 	char *name;
1411 	struct p9_fid *oldfid;
1412 
1413 	p9_debug(P9_DEBUG_VFS, " %lu,%s,%s\n",
1414 		 dir->i_ino, dentry->d_name.name, old_dentry->d_name.name);
1415 
1416 	oldfid = v9fs_fid_clone(old_dentry);
1417 	if (IS_ERR(oldfid))
1418 		return PTR_ERR(oldfid);
1419 
1420 	name = __getname();
1421 	if (unlikely(!name)) {
1422 		retval = -ENOMEM;
1423 		goto clunk_fid;
1424 	}
1425 
1426 	sprintf(name, "%d\n", oldfid->fid);
1427 	retval = v9fs_vfs_mkspecial(dir, dentry, P9_DMLINK, name);
1428 	__putname(name);
1429 	if (!retval) {
1430 		v9fs_refresh_inode(oldfid, old_dentry->d_inode);
1431 		v9fs_invalidate_inode_attr(dir);
1432 	}
1433 clunk_fid:
1434 	p9_client_clunk(oldfid);
1435 	return retval;
1436 }
1437 
1438 /**
1439  * v9fs_vfs_mknod - create a special file
1440  * @dir: inode destination for new link
1441  * @dentry: dentry for file
1442  * @mode: mode for creation
1443  * @rdev: device associated with special file
1444  *
1445  */
1446 
1447 static int
1448 v9fs_vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t rdev)
1449 {
1450 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
1451 	int retval;
1452 	char *name;
1453 	u32 perm;
1454 
1455 	p9_debug(P9_DEBUG_VFS, " %lu,%s mode: %hx MAJOR: %u MINOR: %u\n",
1456 		 dir->i_ino, dentry->d_name.name, mode,
1457 		 MAJOR(rdev), MINOR(rdev));
1458 
1459 	if (!new_valid_dev(rdev))
1460 		return -EINVAL;
1461 
1462 	name = __getname();
1463 	if (!name)
1464 		return -ENOMEM;
1465 	/* build extension */
1466 	if (S_ISBLK(mode))
1467 		sprintf(name, "b %u %u", MAJOR(rdev), MINOR(rdev));
1468 	else if (S_ISCHR(mode))
1469 		sprintf(name, "c %u %u", MAJOR(rdev), MINOR(rdev));
1470 	else if (S_ISFIFO(mode))
1471 		*name = 0;
1472 	else if (S_ISSOCK(mode))
1473 		*name = 0;
1474 	else {
1475 		__putname(name);
1476 		return -EINVAL;
1477 	}
1478 
1479 	perm = unixmode2p9mode(v9ses, mode);
1480 	retval = v9fs_vfs_mkspecial(dir, dentry, perm, name);
1481 	__putname(name);
1482 
1483 	return retval;
1484 }
1485 
1486 int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode)
1487 {
1488 	int umode;
1489 	dev_t rdev;
1490 	loff_t i_size;
1491 	struct p9_wstat *st;
1492 	struct v9fs_session_info *v9ses;
1493 
1494 	v9ses = v9fs_inode2v9ses(inode);
1495 	st = p9_client_stat(fid);
1496 	if (IS_ERR(st))
1497 		return PTR_ERR(st);
1498 	/*
1499 	 * Don't update inode if the file type is different
1500 	 */
1501 	umode = p9mode2unixmode(v9ses, st, &rdev);
1502 	if ((inode->i_mode & S_IFMT) != (umode & S_IFMT))
1503 		goto out;
1504 
1505 	spin_lock(&inode->i_lock);
1506 	/*
1507 	 * We don't want to refresh inode->i_size,
1508 	 * because we may have cached data
1509 	 */
1510 	i_size = inode->i_size;
1511 	v9fs_stat2inode(st, inode, inode->i_sb);
1512 	if (v9ses->cache)
1513 		inode->i_size = i_size;
1514 	spin_unlock(&inode->i_lock);
1515 out:
1516 	p9stat_free(st);
1517 	kfree(st);
1518 	return 0;
1519 }
1520 
1521 static const struct inode_operations v9fs_dir_inode_operations_dotu = {
1522 	.create = v9fs_vfs_create,
1523 	.lookup = v9fs_vfs_lookup,
1524 	.atomic_open = v9fs_vfs_atomic_open,
1525 	.symlink = v9fs_vfs_symlink,
1526 	.link = v9fs_vfs_link,
1527 	.unlink = v9fs_vfs_unlink,
1528 	.mkdir = v9fs_vfs_mkdir,
1529 	.rmdir = v9fs_vfs_rmdir,
1530 	.mknod = v9fs_vfs_mknod,
1531 	.rename = v9fs_vfs_rename,
1532 	.getattr = v9fs_vfs_getattr,
1533 	.setattr = v9fs_vfs_setattr,
1534 };
1535 
1536 static const struct inode_operations v9fs_dir_inode_operations = {
1537 	.create = v9fs_vfs_create,
1538 	.lookup = v9fs_vfs_lookup,
1539 	.atomic_open = v9fs_vfs_atomic_open,
1540 	.unlink = v9fs_vfs_unlink,
1541 	.mkdir = v9fs_vfs_mkdir,
1542 	.rmdir = v9fs_vfs_rmdir,
1543 	.mknod = v9fs_vfs_mknod,
1544 	.rename = v9fs_vfs_rename,
1545 	.getattr = v9fs_vfs_getattr,
1546 	.setattr = v9fs_vfs_setattr,
1547 };
1548 
1549 static const struct inode_operations v9fs_file_inode_operations = {
1550 	.getattr = v9fs_vfs_getattr,
1551 	.setattr = v9fs_vfs_setattr,
1552 };
1553 
1554 static const struct inode_operations v9fs_symlink_inode_operations = {
1555 	.readlink = generic_readlink,
1556 	.follow_link = v9fs_vfs_follow_link,
1557 	.put_link = v9fs_vfs_put_link,
1558 	.getattr = v9fs_vfs_getattr,
1559 	.setattr = v9fs_vfs_setattr,
1560 };
1561 
1562