xref: /openbmc/linux/fs/kernfs/dir.c (revision aea95c68)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * fs/kernfs/dir.c - kernfs directory implementation
4  *
5  * Copyright (c) 2001-3 Patrick Mochel
6  * Copyright (c) 2007 SUSE Linux Products GmbH
7  * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
8  */
9 
10 #include <linux/sched.h>
11 #include <linux/fs.h>
12 #include <linux/namei.h>
13 #include <linux/idr.h>
14 #include <linux/slab.h>
15 #include <linux/security.h>
16 #include <linux/hash.h>
17 
18 #include "kernfs-internal.h"
19 
20 static DEFINE_RWLOCK(kernfs_rename_lock);	/* kn->parent and ->name */
21 /*
22  * Don't use rename_lock to piggy back on pr_cont_buf. We don't want to
23  * call pr_cont() while holding rename_lock. Because sometimes pr_cont()
24  * will perform wakeups when releasing console_sem. Holding rename_lock
25  * will introduce deadlock if the scheduler reads the kernfs_name in the
26  * wakeup path.
27  */
28 static DEFINE_SPINLOCK(kernfs_pr_cont_lock);
29 static char kernfs_pr_cont_buf[PATH_MAX];	/* protected by pr_cont_lock */
30 static DEFINE_SPINLOCK(kernfs_idr_lock);	/* root->ino_idr */
31 
32 #define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb)
33 
__kernfs_active(struct kernfs_node * kn)34 static bool __kernfs_active(struct kernfs_node *kn)
35 {
36 	return atomic_read(&kn->active) >= 0;
37 }
38 
kernfs_active(struct kernfs_node * kn)39 static bool kernfs_active(struct kernfs_node *kn)
40 {
41 	lockdep_assert_held(&kernfs_root(kn)->kernfs_rwsem);
42 	return __kernfs_active(kn);
43 }
44 
kernfs_lockdep(struct kernfs_node * kn)45 static bool kernfs_lockdep(struct kernfs_node *kn)
46 {
47 #ifdef CONFIG_DEBUG_LOCK_ALLOC
48 	return kn->flags & KERNFS_LOCKDEP;
49 #else
50 	return false;
51 #endif
52 }
53 
kernfs_name_locked(struct kernfs_node * kn,char * buf,size_t buflen)54 static int kernfs_name_locked(struct kernfs_node *kn, char *buf, size_t buflen)
55 {
56 	if (!kn)
57 		return strlcpy(buf, "(null)", buflen);
58 
59 	return strlcpy(buf, kn->parent ? kn->name : "/", buflen);
60 }
61 
62 /* kernfs_node_depth - compute depth from @from to @to */
kernfs_depth(struct kernfs_node * from,struct kernfs_node * to)63 static size_t kernfs_depth(struct kernfs_node *from, struct kernfs_node *to)
64 {
65 	size_t depth = 0;
66 
67 	while (to->parent && to != from) {
68 		depth++;
69 		to = to->parent;
70 	}
71 	return depth;
72 }
73 
kernfs_common_ancestor(struct kernfs_node * a,struct kernfs_node * b)74 static struct kernfs_node *kernfs_common_ancestor(struct kernfs_node *a,
75 						  struct kernfs_node *b)
76 {
77 	size_t da, db;
78 	struct kernfs_root *ra = kernfs_root(a), *rb = kernfs_root(b);
79 
80 	if (ra != rb)
81 		return NULL;
82 
83 	da = kernfs_depth(ra->kn, a);
84 	db = kernfs_depth(rb->kn, b);
85 
86 	while (da > db) {
87 		a = a->parent;
88 		da--;
89 	}
90 	while (db > da) {
91 		b = b->parent;
92 		db--;
93 	}
94 
95 	/* worst case b and a will be the same at root */
96 	while (b != a) {
97 		b = b->parent;
98 		a = a->parent;
99 	}
100 
101 	return a;
102 }
103 
104 /**
105  * kernfs_path_from_node_locked - find a pseudo-absolute path to @kn_to,
106  * where kn_from is treated as root of the path.
107  * @kn_from: kernfs node which should be treated as root for the path
108  * @kn_to: kernfs node to which path is needed
109  * @buf: buffer to copy the path into
110  * @buflen: size of @buf
111  *
112  * We need to handle couple of scenarios here:
113  * [1] when @kn_from is an ancestor of @kn_to at some level
114  * kn_from: /n1/n2/n3
115  * kn_to:   /n1/n2/n3/n4/n5
116  * result:  /n4/n5
117  *
118  * [2] when @kn_from is on a different hierarchy and we need to find common
119  * ancestor between @kn_from and @kn_to.
120  * kn_from: /n1/n2/n3/n4
121  * kn_to:   /n1/n2/n5
122  * result:  /../../n5
123  * OR
124  * kn_from: /n1/n2/n3/n4/n5   [depth=5]
125  * kn_to:   /n1/n2/n3         [depth=3]
126  * result:  /../..
127  *
128  * [3] when @kn_to is %NULL result will be "(null)"
129  *
130  * Return: the length of the constructed path.  If the path would have been
131  * greater than @buflen, @buf contains the truncated path with the trailing
132  * '\0'.  On error, -errno is returned.
133  */
kernfs_path_from_node_locked(struct kernfs_node * kn_to,struct kernfs_node * kn_from,char * buf,size_t buflen)134 static int kernfs_path_from_node_locked(struct kernfs_node *kn_to,
135 					struct kernfs_node *kn_from,
136 					char *buf, size_t buflen)
137 {
138 	struct kernfs_node *kn, *common;
139 	const char parent_str[] = "/..";
140 	size_t depth_from, depth_to, len = 0;
141 	ssize_t copied;
142 	int i, j;
143 
144 	if (!kn_to)
145 		return strscpy(buf, "(null)", buflen);
146 
147 	if (!kn_from)
148 		kn_from = kernfs_root(kn_to)->kn;
149 
150 	if (kn_from == kn_to)
151 		return strscpy(buf, "/", buflen);
152 
153 	common = kernfs_common_ancestor(kn_from, kn_to);
154 	if (WARN_ON(!common))
155 		return -EINVAL;
156 
157 	depth_to = kernfs_depth(common, kn_to);
158 	depth_from = kernfs_depth(common, kn_from);
159 
160 	buf[0] = '\0';
161 
162 	for (i = 0; i < depth_from; i++) {
163 		copied = strscpy(buf + len, parent_str, buflen - len);
164 		if (copied < 0)
165 			return copied;
166 		len += copied;
167 	}
168 
169 	/* Calculate how many bytes we need for the rest */
170 	for (i = depth_to - 1; i >= 0; i--) {
171 		for (kn = kn_to, j = 0; j < i; j++)
172 			kn = kn->parent;
173 
174 		len += scnprintf(buf + len, buflen - len, "/%s", kn->name);
175 	}
176 
177 	return len;
178 }
179 
180 /**
181  * kernfs_name - obtain the name of a given node
182  * @kn: kernfs_node of interest
183  * @buf: buffer to copy @kn's name into
184  * @buflen: size of @buf
185  *
186  * Copies the name of @kn into @buf of @buflen bytes.  The behavior is
187  * similar to strlcpy().
188  *
189  * Fills buffer with "(null)" if @kn is %NULL.
190  *
191  * Return: the length of @kn's name and if @buf isn't long enough,
192  * it's filled up to @buflen-1 and nul terminated.
193  *
194  * This function can be called from any context.
195  */
kernfs_name(struct kernfs_node * kn,char * buf,size_t buflen)196 int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
197 {
198 	unsigned long flags;
199 	int ret;
200 
201 	read_lock_irqsave(&kernfs_rename_lock, flags);
202 	ret = kernfs_name_locked(kn, buf, buflen);
203 	read_unlock_irqrestore(&kernfs_rename_lock, flags);
204 	return ret;
205 }
206 
207 /**
208  * kernfs_path_from_node - build path of node @to relative to @from.
209  * @from: parent kernfs_node relative to which we need to build the path
210  * @to: kernfs_node of interest
211  * @buf: buffer to copy @to's path into
212  * @buflen: size of @buf
213  *
214  * Builds @to's path relative to @from in @buf. @from and @to must
215  * be on the same kernfs-root. If @from is not parent of @to, then a relative
216  * path (which includes '..'s) as needed to reach from @from to @to is
217  * returned.
218  *
219  * Return: the length of the constructed path.  If the path would have been
220  * greater than @buflen, @buf contains the truncated path with the trailing
221  * '\0'.  On error, -errno is returned.
222  */
kernfs_path_from_node(struct kernfs_node * to,struct kernfs_node * from,char * buf,size_t buflen)223 int kernfs_path_from_node(struct kernfs_node *to, struct kernfs_node *from,
224 			  char *buf, size_t buflen)
225 {
226 	unsigned long flags;
227 	int ret;
228 
229 	read_lock_irqsave(&kernfs_rename_lock, flags);
230 	ret = kernfs_path_from_node_locked(to, from, buf, buflen);
231 	read_unlock_irqrestore(&kernfs_rename_lock, flags);
232 	return ret;
233 }
234 EXPORT_SYMBOL_GPL(kernfs_path_from_node);
235 
236 /**
237  * pr_cont_kernfs_name - pr_cont name of a kernfs_node
238  * @kn: kernfs_node of interest
239  *
240  * This function can be called from any context.
241  */
pr_cont_kernfs_name(struct kernfs_node * kn)242 void pr_cont_kernfs_name(struct kernfs_node *kn)
243 {
244 	unsigned long flags;
245 
246 	spin_lock_irqsave(&kernfs_pr_cont_lock, flags);
247 
248 	kernfs_name(kn, kernfs_pr_cont_buf, sizeof(kernfs_pr_cont_buf));
249 	pr_cont("%s", kernfs_pr_cont_buf);
250 
251 	spin_unlock_irqrestore(&kernfs_pr_cont_lock, flags);
252 }
253 
254 /**
255  * pr_cont_kernfs_path - pr_cont path of a kernfs_node
256  * @kn: kernfs_node of interest
257  *
258  * This function can be called from any context.
259  */
pr_cont_kernfs_path(struct kernfs_node * kn)260 void pr_cont_kernfs_path(struct kernfs_node *kn)
261 {
262 	unsigned long flags;
263 	int sz;
264 
265 	spin_lock_irqsave(&kernfs_pr_cont_lock, flags);
266 
267 	sz = kernfs_path_from_node(kn, NULL, kernfs_pr_cont_buf,
268 				   sizeof(kernfs_pr_cont_buf));
269 	if (sz < 0) {
270 		if (sz == -E2BIG)
271 			pr_cont("(name too long)");
272 		else
273 			pr_cont("(error)");
274 		goto out;
275 	}
276 
277 	pr_cont("%s", kernfs_pr_cont_buf);
278 
279 out:
280 	spin_unlock_irqrestore(&kernfs_pr_cont_lock, flags);
281 }
282 
283 /**
284  * kernfs_get_parent - determine the parent node and pin it
285  * @kn: kernfs_node of interest
286  *
287  * Determines @kn's parent, pins and returns it.  This function can be
288  * called from any context.
289  *
290  * Return: parent node of @kn
291  */
kernfs_get_parent(struct kernfs_node * kn)292 struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn)
293 {
294 	struct kernfs_node *parent;
295 	unsigned long flags;
296 
297 	read_lock_irqsave(&kernfs_rename_lock, flags);
298 	parent = kn->parent;
299 	kernfs_get(parent);
300 	read_unlock_irqrestore(&kernfs_rename_lock, flags);
301 
302 	return parent;
303 }
304 
305 /**
306  *	kernfs_name_hash - calculate hash of @ns + @name
307  *	@name: Null terminated string to hash
308  *	@ns:   Namespace tag to hash
309  *
310  *	Return: 31-bit hash of ns + name (so it fits in an off_t)
311  */
kernfs_name_hash(const char * name,const void * ns)312 static unsigned int kernfs_name_hash(const char *name, const void *ns)
313 {
314 	unsigned long hash = init_name_hash(ns);
315 	unsigned int len = strlen(name);
316 	while (len--)
317 		hash = partial_name_hash(*name++, hash);
318 	hash = end_name_hash(hash);
319 	hash &= 0x7fffffffU;
320 	/* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */
321 	if (hash < 2)
322 		hash += 2;
323 	if (hash >= INT_MAX)
324 		hash = INT_MAX - 1;
325 	return hash;
326 }
327 
kernfs_name_compare(unsigned int hash,const char * name,const void * ns,const struct kernfs_node * kn)328 static int kernfs_name_compare(unsigned int hash, const char *name,
329 			       const void *ns, const struct kernfs_node *kn)
330 {
331 	if (hash < kn->hash)
332 		return -1;
333 	if (hash > kn->hash)
334 		return 1;
335 	if (ns < kn->ns)
336 		return -1;
337 	if (ns > kn->ns)
338 		return 1;
339 	return strcmp(name, kn->name);
340 }
341 
kernfs_sd_compare(const struct kernfs_node * left,const struct kernfs_node * right)342 static int kernfs_sd_compare(const struct kernfs_node *left,
343 			     const struct kernfs_node *right)
344 {
345 	return kernfs_name_compare(left->hash, left->name, left->ns, right);
346 }
347 
348 /**
349  *	kernfs_link_sibling - link kernfs_node into sibling rbtree
350  *	@kn: kernfs_node of interest
351  *
352  *	Link @kn into its sibling rbtree which starts from
353  *	@kn->parent->dir.children.
354  *
355  *	Locking:
356  *	kernfs_rwsem held exclusive
357  *
358  *	Return:
359  *	%0 on success, -EEXIST on failure.
360  */
kernfs_link_sibling(struct kernfs_node * kn)361 static int kernfs_link_sibling(struct kernfs_node *kn)
362 {
363 	struct rb_node **node = &kn->parent->dir.children.rb_node;
364 	struct rb_node *parent = NULL;
365 
366 	while (*node) {
367 		struct kernfs_node *pos;
368 		int result;
369 
370 		pos = rb_to_kn(*node);
371 		parent = *node;
372 		result = kernfs_sd_compare(kn, pos);
373 		if (result < 0)
374 			node = &pos->rb.rb_left;
375 		else if (result > 0)
376 			node = &pos->rb.rb_right;
377 		else
378 			return -EEXIST;
379 	}
380 
381 	/* add new node and rebalance the tree */
382 	rb_link_node(&kn->rb, parent, node);
383 	rb_insert_color(&kn->rb, &kn->parent->dir.children);
384 
385 	/* successfully added, account subdir number */
386 	down_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
387 	if (kernfs_type(kn) == KERNFS_DIR)
388 		kn->parent->dir.subdirs++;
389 	kernfs_inc_rev(kn->parent);
390 	up_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
391 
392 	return 0;
393 }
394 
395 /**
396  *	kernfs_unlink_sibling - unlink kernfs_node from sibling rbtree
397  *	@kn: kernfs_node of interest
398  *
399  *	Try to unlink @kn from its sibling rbtree which starts from
400  *	kn->parent->dir.children.
401  *
402  *	Return: %true if @kn was actually removed,
403  *	%false if @kn wasn't on the rbtree.
404  *
405  *	Locking:
406  *	kernfs_rwsem held exclusive
407  */
kernfs_unlink_sibling(struct kernfs_node * kn)408 static bool kernfs_unlink_sibling(struct kernfs_node *kn)
409 {
410 	if (RB_EMPTY_NODE(&kn->rb))
411 		return false;
412 
413 	down_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
414 	if (kernfs_type(kn) == KERNFS_DIR)
415 		kn->parent->dir.subdirs--;
416 	kernfs_inc_rev(kn->parent);
417 	up_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
418 
419 	rb_erase(&kn->rb, &kn->parent->dir.children);
420 	RB_CLEAR_NODE(&kn->rb);
421 	return true;
422 }
423 
424 /**
425  *	kernfs_get_active - get an active reference to kernfs_node
426  *	@kn: kernfs_node to get an active reference to
427  *
428  *	Get an active reference of @kn.  This function is noop if @kn
429  *	is %NULL.
430  *
431  *	Return:
432  *	Pointer to @kn on success, %NULL on failure.
433  */
kernfs_get_active(struct kernfs_node * kn)434 struct kernfs_node *kernfs_get_active(struct kernfs_node *kn)
435 {
436 	if (unlikely(!kn))
437 		return NULL;
438 
439 	if (!atomic_inc_unless_negative(&kn->active))
440 		return NULL;
441 
442 	if (kernfs_lockdep(kn))
443 		rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_);
444 	return kn;
445 }
446 
447 /**
448  *	kernfs_put_active - put an active reference to kernfs_node
449  *	@kn: kernfs_node to put an active reference to
450  *
451  *	Put an active reference to @kn.  This function is noop if @kn
452  *	is %NULL.
453  */
kernfs_put_active(struct kernfs_node * kn)454 void kernfs_put_active(struct kernfs_node *kn)
455 {
456 	int v;
457 
458 	if (unlikely(!kn))
459 		return;
460 
461 	if (kernfs_lockdep(kn))
462 		rwsem_release(&kn->dep_map, _RET_IP_);
463 	v = atomic_dec_return(&kn->active);
464 	if (likely(v != KN_DEACTIVATED_BIAS))
465 		return;
466 
467 	wake_up_all(&kernfs_root(kn)->deactivate_waitq);
468 }
469 
470 /**
471  * kernfs_drain - drain kernfs_node
472  * @kn: kernfs_node to drain
473  *
474  * Drain existing usages and nuke all existing mmaps of @kn.  Multiple
475  * removers may invoke this function concurrently on @kn and all will
476  * return after draining is complete.
477  */
kernfs_drain(struct kernfs_node * kn)478 static void kernfs_drain(struct kernfs_node *kn)
479 	__releases(&kernfs_root(kn)->kernfs_rwsem)
480 	__acquires(&kernfs_root(kn)->kernfs_rwsem)
481 {
482 	struct kernfs_root *root = kernfs_root(kn);
483 
484 	lockdep_assert_held_write(&root->kernfs_rwsem);
485 	WARN_ON_ONCE(kernfs_active(kn));
486 
487 	/*
488 	 * Skip draining if already fully drained. This avoids draining and its
489 	 * lockdep annotations for nodes which have never been activated
490 	 * allowing embedding kernfs_remove() in create error paths without
491 	 * worrying about draining.
492 	 */
493 	if (atomic_read(&kn->active) == KN_DEACTIVATED_BIAS &&
494 	    !kernfs_should_drain_open_files(kn))
495 		return;
496 
497 	up_write(&root->kernfs_rwsem);
498 
499 	if (kernfs_lockdep(kn)) {
500 		rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_);
501 		if (atomic_read(&kn->active) != KN_DEACTIVATED_BIAS)
502 			lock_contended(&kn->dep_map, _RET_IP_);
503 	}
504 
505 	wait_event(root->deactivate_waitq,
506 		   atomic_read(&kn->active) == KN_DEACTIVATED_BIAS);
507 
508 	if (kernfs_lockdep(kn)) {
509 		lock_acquired(&kn->dep_map, _RET_IP_);
510 		rwsem_release(&kn->dep_map, _RET_IP_);
511 	}
512 
513 	if (kernfs_should_drain_open_files(kn))
514 		kernfs_drain_open_files(kn);
515 
516 	down_write(&root->kernfs_rwsem);
517 }
518 
519 /**
520  * kernfs_get - get a reference count on a kernfs_node
521  * @kn: the target kernfs_node
522  */
kernfs_get(struct kernfs_node * kn)523 void kernfs_get(struct kernfs_node *kn)
524 {
525 	if (kn) {
526 		WARN_ON(!atomic_read(&kn->count));
527 		atomic_inc(&kn->count);
528 	}
529 }
530 EXPORT_SYMBOL_GPL(kernfs_get);
531 
kernfs_free_rcu(struct rcu_head * rcu)532 static void kernfs_free_rcu(struct rcu_head *rcu)
533 {
534 	struct kernfs_node *kn = container_of(rcu, struct kernfs_node, rcu);
535 
536 	kfree_const(kn->name);
537 
538 	if (kn->iattr) {
539 		simple_xattrs_free(&kn->iattr->xattrs, NULL);
540 		kmem_cache_free(kernfs_iattrs_cache, kn->iattr);
541 	}
542 
543 	kmem_cache_free(kernfs_node_cache, kn);
544 }
545 
546 /**
547  * kernfs_put - put a reference count on a kernfs_node
548  * @kn: the target kernfs_node
549  *
550  * Put a reference count of @kn and destroy it if it reached zero.
551  */
kernfs_put(struct kernfs_node * kn)552 void kernfs_put(struct kernfs_node *kn)
553 {
554 	struct kernfs_node *parent;
555 	struct kernfs_root *root;
556 
557 	if (!kn || !atomic_dec_and_test(&kn->count))
558 		return;
559 	root = kernfs_root(kn);
560  repeat:
561 	/*
562 	 * Moving/renaming is always done while holding reference.
563 	 * kn->parent won't change beneath us.
564 	 */
565 	parent = kn->parent;
566 
567 	WARN_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS,
568 		  "kernfs_put: %s/%s: released with incorrect active_ref %d\n",
569 		  parent ? parent->name : "", kn->name, atomic_read(&kn->active));
570 
571 	if (kernfs_type(kn) == KERNFS_LINK)
572 		kernfs_put(kn->symlink.target_kn);
573 
574 	spin_lock(&kernfs_idr_lock);
575 	idr_remove(&root->ino_idr, (u32)kernfs_ino(kn));
576 	spin_unlock(&kernfs_idr_lock);
577 
578 	call_rcu(&kn->rcu, kernfs_free_rcu);
579 
580 	kn = parent;
581 	if (kn) {
582 		if (atomic_dec_and_test(&kn->count))
583 			goto repeat;
584 	} else {
585 		/* just released the root kn, free @root too */
586 		idr_destroy(&root->ino_idr);
587 		kfree_rcu(root, rcu);
588 	}
589 }
590 EXPORT_SYMBOL_GPL(kernfs_put);
591 
592 /**
593  * kernfs_node_from_dentry - determine kernfs_node associated with a dentry
594  * @dentry: the dentry in question
595  *
596  * Return: the kernfs_node associated with @dentry.  If @dentry is not a
597  * kernfs one, %NULL is returned.
598  *
599  * While the returned kernfs_node will stay accessible as long as @dentry
600  * is accessible, the returned node can be in any state and the caller is
601  * fully responsible for determining what's accessible.
602  */
kernfs_node_from_dentry(struct dentry * dentry)603 struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
604 {
605 	if (dentry->d_sb->s_op == &kernfs_sops)
606 		return kernfs_dentry_node(dentry);
607 	return NULL;
608 }
609 
__kernfs_new_node(struct kernfs_root * root,struct kernfs_node * parent,const char * name,umode_t mode,kuid_t uid,kgid_t gid,unsigned flags)610 static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
611 					     struct kernfs_node *parent,
612 					     const char *name, umode_t mode,
613 					     kuid_t uid, kgid_t gid,
614 					     unsigned flags)
615 {
616 	struct kernfs_node *kn;
617 	u32 id_highbits;
618 	int ret;
619 
620 	name = kstrdup_const(name, GFP_KERNEL);
621 	if (!name)
622 		return NULL;
623 
624 	kn = kmem_cache_zalloc(kernfs_node_cache, GFP_KERNEL);
625 	if (!kn)
626 		goto err_out1;
627 
628 	idr_preload(GFP_KERNEL);
629 	spin_lock(&kernfs_idr_lock);
630 	ret = idr_alloc_cyclic(&root->ino_idr, kn, 1, 0, GFP_ATOMIC);
631 	if (ret >= 0 && ret < root->last_id_lowbits)
632 		root->id_highbits++;
633 	id_highbits = root->id_highbits;
634 	root->last_id_lowbits = ret;
635 	spin_unlock(&kernfs_idr_lock);
636 	idr_preload_end();
637 	if (ret < 0)
638 		goto err_out2;
639 
640 	kn->id = (u64)id_highbits << 32 | ret;
641 
642 	atomic_set(&kn->count, 1);
643 	atomic_set(&kn->active, KN_DEACTIVATED_BIAS);
644 	RB_CLEAR_NODE(&kn->rb);
645 
646 	kn->name = name;
647 	kn->mode = mode;
648 	kn->flags = flags;
649 
650 	if (!uid_eq(uid, GLOBAL_ROOT_UID) || !gid_eq(gid, GLOBAL_ROOT_GID)) {
651 		struct iattr iattr = {
652 			.ia_valid = ATTR_UID | ATTR_GID,
653 			.ia_uid = uid,
654 			.ia_gid = gid,
655 		};
656 
657 		ret = __kernfs_setattr(kn, &iattr);
658 		if (ret < 0)
659 			goto err_out3;
660 	}
661 
662 	if (parent) {
663 		ret = security_kernfs_init_security(parent, kn);
664 		if (ret)
665 			goto err_out3;
666 	}
667 
668 	return kn;
669 
670  err_out3:
671 	spin_lock(&kernfs_idr_lock);
672 	idr_remove(&root->ino_idr, (u32)kernfs_ino(kn));
673 	spin_unlock(&kernfs_idr_lock);
674  err_out2:
675 	kmem_cache_free(kernfs_node_cache, kn);
676  err_out1:
677 	kfree_const(name);
678 	return NULL;
679 }
680 
kernfs_new_node(struct kernfs_node * parent,const char * name,umode_t mode,kuid_t uid,kgid_t gid,unsigned flags)681 struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
682 				    const char *name, umode_t mode,
683 				    kuid_t uid, kgid_t gid,
684 				    unsigned flags)
685 {
686 	struct kernfs_node *kn;
687 
688 	if (parent->mode & S_ISGID) {
689 		/* this code block imitates inode_init_owner() for
690 		 * kernfs
691 		 */
692 
693 		if (parent->iattr)
694 			gid = parent->iattr->ia_gid;
695 
696 		if (flags & KERNFS_DIR)
697 			mode |= S_ISGID;
698 	}
699 
700 	kn = __kernfs_new_node(kernfs_root(parent), parent,
701 			       name, mode, uid, gid, flags);
702 	if (kn) {
703 		kernfs_get(parent);
704 		kn->parent = parent;
705 	}
706 	return kn;
707 }
708 
709 /*
710  * kernfs_find_and_get_node_by_id - get kernfs_node from node id
711  * @root: the kernfs root
712  * @id: the target node id
713  *
714  * @id's lower 32bits encode ino and upper gen.  If the gen portion is
715  * zero, all generations are matched.
716  *
717  * Return: %NULL on failure,
718  * otherwise a kernfs node with reference counter incremented.
719  */
kernfs_find_and_get_node_by_id(struct kernfs_root * root,u64 id)720 struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root,
721 						   u64 id)
722 {
723 	struct kernfs_node *kn;
724 	ino_t ino = kernfs_id_ino(id);
725 	u32 gen = kernfs_id_gen(id);
726 
727 	rcu_read_lock();
728 
729 	kn = idr_find(&root->ino_idr, (u32)ino);
730 	if (!kn)
731 		goto err_unlock;
732 
733 	if (sizeof(ino_t) >= sizeof(u64)) {
734 		/* we looked up with the low 32bits, compare the whole */
735 		if (kernfs_ino(kn) != ino)
736 			goto err_unlock;
737 	} else {
738 		/* 0 matches all generations */
739 		if (unlikely(gen && kernfs_gen(kn) != gen))
740 			goto err_unlock;
741 	}
742 
743 	/*
744 	 * We should fail if @kn has never been activated and guarantee success
745 	 * if the caller knows that @kn is active. Both can be achieved by
746 	 * __kernfs_active() which tests @kn->active without kernfs_rwsem.
747 	 */
748 	if (unlikely(!__kernfs_active(kn) || !atomic_inc_not_zero(&kn->count)))
749 		goto err_unlock;
750 
751 	rcu_read_unlock();
752 	return kn;
753 err_unlock:
754 	rcu_read_unlock();
755 	return NULL;
756 }
757 
758 /**
759  *	kernfs_add_one - add kernfs_node to parent without warning
760  *	@kn: kernfs_node to be added
761  *
762  *	The caller must already have initialized @kn->parent.  This
763  *	function increments nlink of the parent's inode if @kn is a
764  *	directory and link into the children list of the parent.
765  *
766  *	Return:
767  *	%0 on success, -EEXIST if entry with the given name already
768  *	exists.
769  */
kernfs_add_one(struct kernfs_node * kn)770 int kernfs_add_one(struct kernfs_node *kn)
771 {
772 	struct kernfs_node *parent = kn->parent;
773 	struct kernfs_root *root = kernfs_root(parent);
774 	struct kernfs_iattrs *ps_iattr;
775 	bool has_ns;
776 	int ret;
777 
778 	down_write(&root->kernfs_rwsem);
779 
780 	ret = -EINVAL;
781 	has_ns = kernfs_ns_enabled(parent);
782 	if (WARN(has_ns != (bool)kn->ns, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n",
783 		 has_ns ? "required" : "invalid", parent->name, kn->name))
784 		goto out_unlock;
785 
786 	if (kernfs_type(parent) != KERNFS_DIR)
787 		goto out_unlock;
788 
789 	ret = -ENOENT;
790 	if (parent->flags & (KERNFS_REMOVING | KERNFS_EMPTY_DIR))
791 		goto out_unlock;
792 
793 	kn->hash = kernfs_name_hash(kn->name, kn->ns);
794 
795 	ret = kernfs_link_sibling(kn);
796 	if (ret)
797 		goto out_unlock;
798 
799 	/* Update timestamps on the parent */
800 	down_write(&root->kernfs_iattr_rwsem);
801 
802 	ps_iattr = parent->iattr;
803 	if (ps_iattr) {
804 		ktime_get_real_ts64(&ps_iattr->ia_ctime);
805 		ps_iattr->ia_mtime = ps_iattr->ia_ctime;
806 	}
807 
808 	up_write(&root->kernfs_iattr_rwsem);
809 	up_write(&root->kernfs_rwsem);
810 
811 	/*
812 	 * Activate the new node unless CREATE_DEACTIVATED is requested.
813 	 * If not activated here, the kernfs user is responsible for
814 	 * activating the node with kernfs_activate().  A node which hasn't
815 	 * been activated is not visible to userland and its removal won't
816 	 * trigger deactivation.
817 	 */
818 	if (!(kernfs_root(kn)->flags & KERNFS_ROOT_CREATE_DEACTIVATED))
819 		kernfs_activate(kn);
820 	return 0;
821 
822 out_unlock:
823 	up_write(&root->kernfs_rwsem);
824 	return ret;
825 }
826 
827 /**
828  * kernfs_find_ns - find kernfs_node with the given name
829  * @parent: kernfs_node to search under
830  * @name: name to look for
831  * @ns: the namespace tag to use
832  *
833  * Look for kernfs_node with name @name under @parent.
834  *
835  * Return: pointer to the found kernfs_node on success, %NULL on failure.
836  */
kernfs_find_ns(struct kernfs_node * parent,const unsigned char * name,const void * ns)837 static struct kernfs_node *kernfs_find_ns(struct kernfs_node *parent,
838 					  const unsigned char *name,
839 					  const void *ns)
840 {
841 	struct rb_node *node = parent->dir.children.rb_node;
842 	bool has_ns = kernfs_ns_enabled(parent);
843 	unsigned int hash;
844 
845 	lockdep_assert_held(&kernfs_root(parent)->kernfs_rwsem);
846 
847 	if (has_ns != (bool)ns) {
848 		WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n",
849 		     has_ns ? "required" : "invalid", parent->name, name);
850 		return NULL;
851 	}
852 
853 	hash = kernfs_name_hash(name, ns);
854 	while (node) {
855 		struct kernfs_node *kn;
856 		int result;
857 
858 		kn = rb_to_kn(node);
859 		result = kernfs_name_compare(hash, name, ns, kn);
860 		if (result < 0)
861 			node = node->rb_left;
862 		else if (result > 0)
863 			node = node->rb_right;
864 		else
865 			return kn;
866 	}
867 	return NULL;
868 }
869 
kernfs_walk_ns(struct kernfs_node * parent,const unsigned char * path,const void * ns)870 static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent,
871 					  const unsigned char *path,
872 					  const void *ns)
873 {
874 	size_t len;
875 	char *p, *name;
876 
877 	lockdep_assert_held_read(&kernfs_root(parent)->kernfs_rwsem);
878 
879 	spin_lock_irq(&kernfs_pr_cont_lock);
880 
881 	len = strlcpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf));
882 
883 	if (len >= sizeof(kernfs_pr_cont_buf)) {
884 		spin_unlock_irq(&kernfs_pr_cont_lock);
885 		return NULL;
886 	}
887 
888 	p = kernfs_pr_cont_buf;
889 
890 	while ((name = strsep(&p, "/")) && parent) {
891 		if (*name == '\0')
892 			continue;
893 		parent = kernfs_find_ns(parent, name, ns);
894 	}
895 
896 	spin_unlock_irq(&kernfs_pr_cont_lock);
897 
898 	return parent;
899 }
900 
901 /**
902  * kernfs_find_and_get_ns - find and get kernfs_node with the given name
903  * @parent: kernfs_node to search under
904  * @name: name to look for
905  * @ns: the namespace tag to use
906  *
907  * Look for kernfs_node with name @name under @parent and get a reference
908  * if found.  This function may sleep.
909  *
910  * Return: pointer to the found kernfs_node on success, %NULL on failure.
911  */
kernfs_find_and_get_ns(struct kernfs_node * parent,const char * name,const void * ns)912 struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
913 					   const char *name, const void *ns)
914 {
915 	struct kernfs_node *kn;
916 	struct kernfs_root *root = kernfs_root(parent);
917 
918 	down_read(&root->kernfs_rwsem);
919 	kn = kernfs_find_ns(parent, name, ns);
920 	kernfs_get(kn);
921 	up_read(&root->kernfs_rwsem);
922 
923 	return kn;
924 }
925 EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns);
926 
927 /**
928  * kernfs_walk_and_get_ns - find and get kernfs_node with the given path
929  * @parent: kernfs_node to search under
930  * @path: path to look for
931  * @ns: the namespace tag to use
932  *
933  * Look for kernfs_node with path @path under @parent and get a reference
934  * if found.  This function may sleep.
935  *
936  * Return: pointer to the found kernfs_node on success, %NULL on failure.
937  */
kernfs_walk_and_get_ns(struct kernfs_node * parent,const char * path,const void * ns)938 struct kernfs_node *kernfs_walk_and_get_ns(struct kernfs_node *parent,
939 					   const char *path, const void *ns)
940 {
941 	struct kernfs_node *kn;
942 	struct kernfs_root *root = kernfs_root(parent);
943 
944 	down_read(&root->kernfs_rwsem);
945 	kn = kernfs_walk_ns(parent, path, ns);
946 	kernfs_get(kn);
947 	up_read(&root->kernfs_rwsem);
948 
949 	return kn;
950 }
951 
952 /**
953  * kernfs_create_root - create a new kernfs hierarchy
954  * @scops: optional syscall operations for the hierarchy
955  * @flags: KERNFS_ROOT_* flags
956  * @priv: opaque data associated with the new directory
957  *
958  * Return: the root of the new hierarchy on success, ERR_PTR() value on
959  * failure.
960  */
kernfs_create_root(struct kernfs_syscall_ops * scops,unsigned int flags,void * priv)961 struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
962 				       unsigned int flags, void *priv)
963 {
964 	struct kernfs_root *root;
965 	struct kernfs_node *kn;
966 
967 	root = kzalloc(sizeof(*root), GFP_KERNEL);
968 	if (!root)
969 		return ERR_PTR(-ENOMEM);
970 
971 	idr_init(&root->ino_idr);
972 	init_rwsem(&root->kernfs_rwsem);
973 	init_rwsem(&root->kernfs_iattr_rwsem);
974 	init_rwsem(&root->kernfs_supers_rwsem);
975 	INIT_LIST_HEAD(&root->supers);
976 
977 	/*
978 	 * On 64bit ino setups, id is ino.  On 32bit, low 32bits are ino.
979 	 * High bits generation.  The starting value for both ino and
980 	 * genenration is 1.  Initialize upper 32bit allocation
981 	 * accordingly.
982 	 */
983 	if (sizeof(ino_t) >= sizeof(u64))
984 		root->id_highbits = 0;
985 	else
986 		root->id_highbits = 1;
987 
988 	kn = __kernfs_new_node(root, NULL, "", S_IFDIR | S_IRUGO | S_IXUGO,
989 			       GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
990 			       KERNFS_DIR);
991 	if (!kn) {
992 		idr_destroy(&root->ino_idr);
993 		kfree(root);
994 		return ERR_PTR(-ENOMEM);
995 	}
996 
997 	kn->priv = priv;
998 	kn->dir.root = root;
999 
1000 	root->syscall_ops = scops;
1001 	root->flags = flags;
1002 	root->kn = kn;
1003 	init_waitqueue_head(&root->deactivate_waitq);
1004 
1005 	if (!(root->flags & KERNFS_ROOT_CREATE_DEACTIVATED))
1006 		kernfs_activate(kn);
1007 
1008 	return root;
1009 }
1010 
1011 /**
1012  * kernfs_destroy_root - destroy a kernfs hierarchy
1013  * @root: root of the hierarchy to destroy
1014  *
1015  * Destroy the hierarchy anchored at @root by removing all existing
1016  * directories and destroying @root.
1017  */
kernfs_destroy_root(struct kernfs_root * root)1018 void kernfs_destroy_root(struct kernfs_root *root)
1019 {
1020 	/*
1021 	 *  kernfs_remove holds kernfs_rwsem from the root so the root
1022 	 *  shouldn't be freed during the operation.
1023 	 */
1024 	kernfs_get(root->kn);
1025 	kernfs_remove(root->kn);
1026 	kernfs_put(root->kn); /* will also free @root */
1027 }
1028 
1029 /**
1030  * kernfs_root_to_node - return the kernfs_node associated with a kernfs_root
1031  * @root: root to use to lookup
1032  *
1033  * Return: @root's kernfs_node
1034  */
kernfs_root_to_node(struct kernfs_root * root)1035 struct kernfs_node *kernfs_root_to_node(struct kernfs_root *root)
1036 {
1037 	return root->kn;
1038 }
1039 
1040 /**
1041  * kernfs_create_dir_ns - create a directory
1042  * @parent: parent in which to create a new directory
1043  * @name: name of the new directory
1044  * @mode: mode of the new directory
1045  * @uid: uid of the new directory
1046  * @gid: gid of the new directory
1047  * @priv: opaque data associated with the new directory
1048  * @ns: optional namespace tag of the directory
1049  *
1050  * Return: the created node on success, ERR_PTR() value on failure.
1051  */
kernfs_create_dir_ns(struct kernfs_node * parent,const char * name,umode_t mode,kuid_t uid,kgid_t gid,void * priv,const void * ns)1052 struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
1053 					 const char *name, umode_t mode,
1054 					 kuid_t uid, kgid_t gid,
1055 					 void *priv, const void *ns)
1056 {
1057 	struct kernfs_node *kn;
1058 	int rc;
1059 
1060 	/* allocate */
1061 	kn = kernfs_new_node(parent, name, mode | S_IFDIR,
1062 			     uid, gid, KERNFS_DIR);
1063 	if (!kn)
1064 		return ERR_PTR(-ENOMEM);
1065 
1066 	kn->dir.root = parent->dir.root;
1067 	kn->ns = ns;
1068 	kn->priv = priv;
1069 
1070 	/* link in */
1071 	rc = kernfs_add_one(kn);
1072 	if (!rc)
1073 		return kn;
1074 
1075 	kernfs_put(kn);
1076 	return ERR_PTR(rc);
1077 }
1078 
1079 /**
1080  * kernfs_create_empty_dir - create an always empty directory
1081  * @parent: parent in which to create a new directory
1082  * @name: name of the new directory
1083  *
1084  * Return: the created node on success, ERR_PTR() value on failure.
1085  */
kernfs_create_empty_dir(struct kernfs_node * parent,const char * name)1086 struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent,
1087 					    const char *name)
1088 {
1089 	struct kernfs_node *kn;
1090 	int rc;
1091 
1092 	/* allocate */
1093 	kn = kernfs_new_node(parent, name, S_IRUGO|S_IXUGO|S_IFDIR,
1094 			     GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, KERNFS_DIR);
1095 	if (!kn)
1096 		return ERR_PTR(-ENOMEM);
1097 
1098 	kn->flags |= KERNFS_EMPTY_DIR;
1099 	kn->dir.root = parent->dir.root;
1100 	kn->ns = NULL;
1101 	kn->priv = NULL;
1102 
1103 	/* link in */
1104 	rc = kernfs_add_one(kn);
1105 	if (!rc)
1106 		return kn;
1107 
1108 	kernfs_put(kn);
1109 	return ERR_PTR(rc);
1110 }
1111 
kernfs_dop_revalidate(struct dentry * dentry,unsigned int flags)1112 static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
1113 {
1114 	struct kernfs_node *kn;
1115 	struct kernfs_root *root;
1116 
1117 	if (flags & LOOKUP_RCU)
1118 		return -ECHILD;
1119 
1120 	/* Negative hashed dentry? */
1121 	if (d_really_is_negative(dentry)) {
1122 		struct kernfs_node *parent;
1123 
1124 		/* If the kernfs parent node has changed discard and
1125 		 * proceed to ->lookup.
1126 		 *
1127 		 * There's nothing special needed here when getting the
1128 		 * dentry parent, even if a concurrent rename is in
1129 		 * progress. That's because the dentry is negative so
1130 		 * it can only be the target of the rename and it will
1131 		 * be doing a d_move() not a replace. Consequently the
1132 		 * dentry d_parent won't change over the d_move().
1133 		 *
1134 		 * Also kernfs negative dentries transitioning from
1135 		 * negative to positive during revalidate won't happen
1136 		 * because they are invalidated on containing directory
1137 		 * changes and the lookup re-done so that a new positive
1138 		 * dentry can be properly created.
1139 		 */
1140 		root = kernfs_root_from_sb(dentry->d_sb);
1141 		down_read(&root->kernfs_rwsem);
1142 		parent = kernfs_dentry_node(dentry->d_parent);
1143 		if (parent) {
1144 			if (kernfs_dir_changed(parent, dentry)) {
1145 				up_read(&root->kernfs_rwsem);
1146 				return 0;
1147 			}
1148 		}
1149 		up_read(&root->kernfs_rwsem);
1150 
1151 		/* The kernfs parent node hasn't changed, leave the
1152 		 * dentry negative and return success.
1153 		 */
1154 		return 1;
1155 	}
1156 
1157 	kn = kernfs_dentry_node(dentry);
1158 	root = kernfs_root(kn);
1159 	down_read(&root->kernfs_rwsem);
1160 
1161 	/* The kernfs node has been deactivated */
1162 	if (!kernfs_active(kn))
1163 		goto out_bad;
1164 
1165 	/* The kernfs node has been moved? */
1166 	if (kernfs_dentry_node(dentry->d_parent) != kn->parent)
1167 		goto out_bad;
1168 
1169 	/* The kernfs node has been renamed */
1170 	if (strcmp(dentry->d_name.name, kn->name) != 0)
1171 		goto out_bad;
1172 
1173 	/* The kernfs node has been moved to a different namespace */
1174 	if (kn->parent && kernfs_ns_enabled(kn->parent) &&
1175 	    kernfs_info(dentry->d_sb)->ns != kn->ns)
1176 		goto out_bad;
1177 
1178 	up_read(&root->kernfs_rwsem);
1179 	return 1;
1180 out_bad:
1181 	up_read(&root->kernfs_rwsem);
1182 	return 0;
1183 }
1184 
1185 const struct dentry_operations kernfs_dops = {
1186 	.d_revalidate	= kernfs_dop_revalidate,
1187 };
1188 
kernfs_iop_lookup(struct inode * dir,struct dentry * dentry,unsigned int flags)1189 static struct dentry *kernfs_iop_lookup(struct inode *dir,
1190 					struct dentry *dentry,
1191 					unsigned int flags)
1192 {
1193 	struct kernfs_node *parent = dir->i_private;
1194 	struct kernfs_node *kn;
1195 	struct kernfs_root *root;
1196 	struct inode *inode = NULL;
1197 	const void *ns = NULL;
1198 
1199 	root = kernfs_root(parent);
1200 	down_read(&root->kernfs_rwsem);
1201 	if (kernfs_ns_enabled(parent))
1202 		ns = kernfs_info(dir->i_sb)->ns;
1203 
1204 	kn = kernfs_find_ns(parent, dentry->d_name.name, ns);
1205 	/* attach dentry and inode */
1206 	if (kn) {
1207 		/* Inactive nodes are invisible to the VFS so don't
1208 		 * create a negative.
1209 		 */
1210 		if (!kernfs_active(kn)) {
1211 			up_read(&root->kernfs_rwsem);
1212 			return NULL;
1213 		}
1214 		inode = kernfs_get_inode(dir->i_sb, kn);
1215 		if (!inode)
1216 			inode = ERR_PTR(-ENOMEM);
1217 	}
1218 	/*
1219 	 * Needed for negative dentry validation.
1220 	 * The negative dentry can be created in kernfs_iop_lookup()
1221 	 * or transforms from positive dentry in dentry_unlink_inode()
1222 	 * called from vfs_rmdir().
1223 	 */
1224 	if (!IS_ERR(inode))
1225 		kernfs_set_rev(parent, dentry);
1226 	up_read(&root->kernfs_rwsem);
1227 
1228 	/* instantiate and hash (possibly negative) dentry */
1229 	return d_splice_alias(inode, dentry);
1230 }
1231 
kernfs_iop_mkdir(struct mnt_idmap * idmap,struct inode * dir,struct dentry * dentry,umode_t mode)1232 static int kernfs_iop_mkdir(struct mnt_idmap *idmap,
1233 			    struct inode *dir, struct dentry *dentry,
1234 			    umode_t mode)
1235 {
1236 	struct kernfs_node *parent = dir->i_private;
1237 	struct kernfs_syscall_ops *scops = kernfs_root(parent)->syscall_ops;
1238 	int ret;
1239 
1240 	if (!scops || !scops->mkdir)
1241 		return -EPERM;
1242 
1243 	if (!kernfs_get_active(parent))
1244 		return -ENODEV;
1245 
1246 	ret = scops->mkdir(parent, dentry->d_name.name, mode);
1247 
1248 	kernfs_put_active(parent);
1249 	return ret;
1250 }
1251 
kernfs_iop_rmdir(struct inode * dir,struct dentry * dentry)1252 static int kernfs_iop_rmdir(struct inode *dir, struct dentry *dentry)
1253 {
1254 	struct kernfs_node *kn  = kernfs_dentry_node(dentry);
1255 	struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops;
1256 	int ret;
1257 
1258 	if (!scops || !scops->rmdir)
1259 		return -EPERM;
1260 
1261 	if (!kernfs_get_active(kn))
1262 		return -ENODEV;
1263 
1264 	ret = scops->rmdir(kn);
1265 
1266 	kernfs_put_active(kn);
1267 	return ret;
1268 }
1269 
kernfs_iop_rename(struct mnt_idmap * idmap,struct inode * old_dir,struct dentry * old_dentry,struct inode * new_dir,struct dentry * new_dentry,unsigned int flags)1270 static int kernfs_iop_rename(struct mnt_idmap *idmap,
1271 			     struct inode *old_dir, struct dentry *old_dentry,
1272 			     struct inode *new_dir, struct dentry *new_dentry,
1273 			     unsigned int flags)
1274 {
1275 	struct kernfs_node *kn = kernfs_dentry_node(old_dentry);
1276 	struct kernfs_node *new_parent = new_dir->i_private;
1277 	struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops;
1278 	int ret;
1279 
1280 	if (flags)
1281 		return -EINVAL;
1282 
1283 	if (!scops || !scops->rename)
1284 		return -EPERM;
1285 
1286 	if (!kernfs_get_active(kn))
1287 		return -ENODEV;
1288 
1289 	if (!kernfs_get_active(new_parent)) {
1290 		kernfs_put_active(kn);
1291 		return -ENODEV;
1292 	}
1293 
1294 	ret = scops->rename(kn, new_parent, new_dentry->d_name.name);
1295 
1296 	kernfs_put_active(new_parent);
1297 	kernfs_put_active(kn);
1298 	return ret;
1299 }
1300 
1301 const struct inode_operations kernfs_dir_iops = {
1302 	.lookup		= kernfs_iop_lookup,
1303 	.permission	= kernfs_iop_permission,
1304 	.setattr	= kernfs_iop_setattr,
1305 	.getattr	= kernfs_iop_getattr,
1306 	.listxattr	= kernfs_iop_listxattr,
1307 
1308 	.mkdir		= kernfs_iop_mkdir,
1309 	.rmdir		= kernfs_iop_rmdir,
1310 	.rename		= kernfs_iop_rename,
1311 };
1312 
kernfs_leftmost_descendant(struct kernfs_node * pos)1313 static struct kernfs_node *kernfs_leftmost_descendant(struct kernfs_node *pos)
1314 {
1315 	struct kernfs_node *last;
1316 
1317 	while (true) {
1318 		struct rb_node *rbn;
1319 
1320 		last = pos;
1321 
1322 		if (kernfs_type(pos) != KERNFS_DIR)
1323 			break;
1324 
1325 		rbn = rb_first(&pos->dir.children);
1326 		if (!rbn)
1327 			break;
1328 
1329 		pos = rb_to_kn(rbn);
1330 	}
1331 
1332 	return last;
1333 }
1334 
1335 /**
1336  * kernfs_next_descendant_post - find the next descendant for post-order walk
1337  * @pos: the current position (%NULL to initiate traversal)
1338  * @root: kernfs_node whose descendants to walk
1339  *
1340  * Find the next descendant to visit for post-order traversal of @root's
1341  * descendants.  @root is included in the iteration and the last node to be
1342  * visited.
1343  *
1344  * Return: the next descendant to visit or %NULL when done.
1345  */
kernfs_next_descendant_post(struct kernfs_node * pos,struct kernfs_node * root)1346 static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos,
1347 						       struct kernfs_node *root)
1348 {
1349 	struct rb_node *rbn;
1350 
1351 	lockdep_assert_held_write(&kernfs_root(root)->kernfs_rwsem);
1352 
1353 	/* if first iteration, visit leftmost descendant which may be root */
1354 	if (!pos)
1355 		return kernfs_leftmost_descendant(root);
1356 
1357 	/* if we visited @root, we're done */
1358 	if (pos == root)
1359 		return NULL;
1360 
1361 	/* if there's an unvisited sibling, visit its leftmost descendant */
1362 	rbn = rb_next(&pos->rb);
1363 	if (rbn)
1364 		return kernfs_leftmost_descendant(rb_to_kn(rbn));
1365 
1366 	/* no sibling left, visit parent */
1367 	return pos->parent;
1368 }
1369 
kernfs_activate_one(struct kernfs_node * kn)1370 static void kernfs_activate_one(struct kernfs_node *kn)
1371 {
1372 	lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem);
1373 
1374 	kn->flags |= KERNFS_ACTIVATED;
1375 
1376 	if (kernfs_active(kn) || (kn->flags & (KERNFS_HIDDEN | KERNFS_REMOVING)))
1377 		return;
1378 
1379 	WARN_ON_ONCE(kn->parent && RB_EMPTY_NODE(&kn->rb));
1380 	WARN_ON_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS);
1381 
1382 	atomic_sub(KN_DEACTIVATED_BIAS, &kn->active);
1383 }
1384 
1385 /**
1386  * kernfs_activate - activate a node which started deactivated
1387  * @kn: kernfs_node whose subtree is to be activated
1388  *
1389  * If the root has KERNFS_ROOT_CREATE_DEACTIVATED set, a newly created node
1390  * needs to be explicitly activated.  A node which hasn't been activated
1391  * isn't visible to userland and deactivation is skipped during its
1392  * removal.  This is useful to construct atomic init sequences where
1393  * creation of multiple nodes should either succeed or fail atomically.
1394  *
1395  * The caller is responsible for ensuring that this function is not called
1396  * after kernfs_remove*() is invoked on @kn.
1397  */
kernfs_activate(struct kernfs_node * kn)1398 void kernfs_activate(struct kernfs_node *kn)
1399 {
1400 	struct kernfs_node *pos;
1401 	struct kernfs_root *root = kernfs_root(kn);
1402 
1403 	down_write(&root->kernfs_rwsem);
1404 
1405 	pos = NULL;
1406 	while ((pos = kernfs_next_descendant_post(pos, kn)))
1407 		kernfs_activate_one(pos);
1408 
1409 	up_write(&root->kernfs_rwsem);
1410 }
1411 
1412 /**
1413  * kernfs_show - show or hide a node
1414  * @kn: kernfs_node to show or hide
1415  * @show: whether to show or hide
1416  *
1417  * If @show is %false, @kn is marked hidden and deactivated. A hidden node is
1418  * ignored in future activaitons. If %true, the mark is removed and activation
1419  * state is restored. This function won't implicitly activate a new node in a
1420  * %KERNFS_ROOT_CREATE_DEACTIVATED root which hasn't been activated yet.
1421  *
1422  * To avoid recursion complexities, directories aren't supported for now.
1423  */
kernfs_show(struct kernfs_node * kn,bool show)1424 void kernfs_show(struct kernfs_node *kn, bool show)
1425 {
1426 	struct kernfs_root *root = kernfs_root(kn);
1427 
1428 	if (WARN_ON_ONCE(kernfs_type(kn) == KERNFS_DIR))
1429 		return;
1430 
1431 	down_write(&root->kernfs_rwsem);
1432 
1433 	if (show) {
1434 		kn->flags &= ~KERNFS_HIDDEN;
1435 		if (kn->flags & KERNFS_ACTIVATED)
1436 			kernfs_activate_one(kn);
1437 	} else {
1438 		kn->flags |= KERNFS_HIDDEN;
1439 		if (kernfs_active(kn))
1440 			atomic_add(KN_DEACTIVATED_BIAS, &kn->active);
1441 		kernfs_drain(kn);
1442 	}
1443 
1444 	up_write(&root->kernfs_rwsem);
1445 }
1446 
__kernfs_remove(struct kernfs_node * kn)1447 static void __kernfs_remove(struct kernfs_node *kn)
1448 {
1449 	struct kernfs_node *pos;
1450 
1451 	/* Short-circuit if non-root @kn has already finished removal. */
1452 	if (!kn)
1453 		return;
1454 
1455 	lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem);
1456 
1457 	/*
1458 	 * This is for kernfs_remove_self() which plays with active ref
1459 	 * after removal.
1460 	 */
1461 	if (kn->parent && RB_EMPTY_NODE(&kn->rb))
1462 		return;
1463 
1464 	pr_debug("kernfs %s: removing\n", kn->name);
1465 
1466 	/* prevent new usage by marking all nodes removing and deactivating */
1467 	pos = NULL;
1468 	while ((pos = kernfs_next_descendant_post(pos, kn))) {
1469 		pos->flags |= KERNFS_REMOVING;
1470 		if (kernfs_active(pos))
1471 			atomic_add(KN_DEACTIVATED_BIAS, &pos->active);
1472 	}
1473 
1474 	/* deactivate and unlink the subtree node-by-node */
1475 	do {
1476 		pos = kernfs_leftmost_descendant(kn);
1477 
1478 		/*
1479 		 * kernfs_drain() may drop kernfs_rwsem temporarily and @pos's
1480 		 * base ref could have been put by someone else by the time
1481 		 * the function returns.  Make sure it doesn't go away
1482 		 * underneath us.
1483 		 */
1484 		kernfs_get(pos);
1485 
1486 		kernfs_drain(pos);
1487 
1488 		/*
1489 		 * kernfs_unlink_sibling() succeeds once per node.  Use it
1490 		 * to decide who's responsible for cleanups.
1491 		 */
1492 		if (!pos->parent || kernfs_unlink_sibling(pos)) {
1493 			struct kernfs_iattrs *ps_iattr =
1494 				pos->parent ? pos->parent->iattr : NULL;
1495 
1496 			/* update timestamps on the parent */
1497 			down_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
1498 
1499 			if (ps_iattr) {
1500 				ktime_get_real_ts64(&ps_iattr->ia_ctime);
1501 				ps_iattr->ia_mtime = ps_iattr->ia_ctime;
1502 			}
1503 
1504 			up_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
1505 			kernfs_put(pos);
1506 		}
1507 
1508 		kernfs_put(pos);
1509 	} while (pos != kn);
1510 }
1511 
1512 /**
1513  * kernfs_remove - remove a kernfs_node recursively
1514  * @kn: the kernfs_node to remove
1515  *
1516  * Remove @kn along with all its subdirectories and files.
1517  */
kernfs_remove(struct kernfs_node * kn)1518 void kernfs_remove(struct kernfs_node *kn)
1519 {
1520 	struct kernfs_root *root;
1521 
1522 	if (!kn)
1523 		return;
1524 
1525 	root = kernfs_root(kn);
1526 
1527 	down_write(&root->kernfs_rwsem);
1528 	__kernfs_remove(kn);
1529 	up_write(&root->kernfs_rwsem);
1530 }
1531 
1532 /**
1533  * kernfs_break_active_protection - break out of active protection
1534  * @kn: the self kernfs_node
1535  *
1536  * The caller must be running off of a kernfs operation which is invoked
1537  * with an active reference - e.g. one of kernfs_ops.  Each invocation of
1538  * this function must also be matched with an invocation of
1539  * kernfs_unbreak_active_protection().
1540  *
1541  * This function releases the active reference of @kn the caller is
1542  * holding.  Once this function is called, @kn may be removed at any point
1543  * and the caller is solely responsible for ensuring that the objects it
1544  * dereferences are accessible.
1545  */
kernfs_break_active_protection(struct kernfs_node * kn)1546 void kernfs_break_active_protection(struct kernfs_node *kn)
1547 {
1548 	/*
1549 	 * Take out ourself out of the active ref dependency chain.  If
1550 	 * we're called without an active ref, lockdep will complain.
1551 	 */
1552 	kernfs_put_active(kn);
1553 }
1554 
1555 /**
1556  * kernfs_unbreak_active_protection - undo kernfs_break_active_protection()
1557  * @kn: the self kernfs_node
1558  *
1559  * If kernfs_break_active_protection() was called, this function must be
1560  * invoked before finishing the kernfs operation.  Note that while this
1561  * function restores the active reference, it doesn't and can't actually
1562  * restore the active protection - @kn may already or be in the process of
1563  * being removed.  Once kernfs_break_active_protection() is invoked, that
1564  * protection is irreversibly gone for the kernfs operation instance.
1565  *
1566  * While this function may be called at any point after
1567  * kernfs_break_active_protection() is invoked, its most useful location
1568  * would be right before the enclosing kernfs operation returns.
1569  */
kernfs_unbreak_active_protection(struct kernfs_node * kn)1570 void kernfs_unbreak_active_protection(struct kernfs_node *kn)
1571 {
1572 	/*
1573 	 * @kn->active could be in any state; however, the increment we do
1574 	 * here will be undone as soon as the enclosing kernfs operation
1575 	 * finishes and this temporary bump can't break anything.  If @kn
1576 	 * is alive, nothing changes.  If @kn is being deactivated, the
1577 	 * soon-to-follow put will either finish deactivation or restore
1578 	 * deactivated state.  If @kn is already removed, the temporary
1579 	 * bump is guaranteed to be gone before @kn is released.
1580 	 */
1581 	atomic_inc(&kn->active);
1582 	if (kernfs_lockdep(kn))
1583 		rwsem_acquire(&kn->dep_map, 0, 1, _RET_IP_);
1584 }
1585 
1586 /**
1587  * kernfs_remove_self - remove a kernfs_node from its own method
1588  * @kn: the self kernfs_node to remove
1589  *
1590  * The caller must be running off of a kernfs operation which is invoked
1591  * with an active reference - e.g. one of kernfs_ops.  This can be used to
1592  * implement a file operation which deletes itself.
1593  *
1594  * For example, the "delete" file for a sysfs device directory can be
1595  * implemented by invoking kernfs_remove_self() on the "delete" file
1596  * itself.  This function breaks the circular dependency of trying to
1597  * deactivate self while holding an active ref itself.  It isn't necessary
1598  * to modify the usual removal path to use kernfs_remove_self().  The
1599  * "delete" implementation can simply invoke kernfs_remove_self() on self
1600  * before proceeding with the usual removal path.  kernfs will ignore later
1601  * kernfs_remove() on self.
1602  *
1603  * kernfs_remove_self() can be called multiple times concurrently on the
1604  * same kernfs_node.  Only the first one actually performs removal and
1605  * returns %true.  All others will wait until the kernfs operation which
1606  * won self-removal finishes and return %false.  Note that the losers wait
1607  * for the completion of not only the winning kernfs_remove_self() but also
1608  * the whole kernfs_ops which won the arbitration.  This can be used to
1609  * guarantee, for example, all concurrent writes to a "delete" file to
1610  * finish only after the whole operation is complete.
1611  *
1612  * Return: %true if @kn is removed by this call, otherwise %false.
1613  */
kernfs_remove_self(struct kernfs_node * kn)1614 bool kernfs_remove_self(struct kernfs_node *kn)
1615 {
1616 	bool ret;
1617 	struct kernfs_root *root = kernfs_root(kn);
1618 
1619 	down_write(&root->kernfs_rwsem);
1620 	kernfs_break_active_protection(kn);
1621 
1622 	/*
1623 	 * SUICIDAL is used to arbitrate among competing invocations.  Only
1624 	 * the first one will actually perform removal.  When the removal
1625 	 * is complete, SUICIDED is set and the active ref is restored
1626 	 * while kernfs_rwsem for held exclusive.  The ones which lost
1627 	 * arbitration waits for SUICIDED && drained which can happen only
1628 	 * after the enclosing kernfs operation which executed the winning
1629 	 * instance of kernfs_remove_self() finished.
1630 	 */
1631 	if (!(kn->flags & KERNFS_SUICIDAL)) {
1632 		kn->flags |= KERNFS_SUICIDAL;
1633 		__kernfs_remove(kn);
1634 		kn->flags |= KERNFS_SUICIDED;
1635 		ret = true;
1636 	} else {
1637 		wait_queue_head_t *waitq = &kernfs_root(kn)->deactivate_waitq;
1638 		DEFINE_WAIT(wait);
1639 
1640 		while (true) {
1641 			prepare_to_wait(waitq, &wait, TASK_UNINTERRUPTIBLE);
1642 
1643 			if ((kn->flags & KERNFS_SUICIDED) &&
1644 			    atomic_read(&kn->active) == KN_DEACTIVATED_BIAS)
1645 				break;
1646 
1647 			up_write(&root->kernfs_rwsem);
1648 			schedule();
1649 			down_write(&root->kernfs_rwsem);
1650 		}
1651 		finish_wait(waitq, &wait);
1652 		WARN_ON_ONCE(!RB_EMPTY_NODE(&kn->rb));
1653 		ret = false;
1654 	}
1655 
1656 	/*
1657 	 * This must be done while kernfs_rwsem held exclusive; otherwise,
1658 	 * waiting for SUICIDED && deactivated could finish prematurely.
1659 	 */
1660 	kernfs_unbreak_active_protection(kn);
1661 
1662 	up_write(&root->kernfs_rwsem);
1663 	return ret;
1664 }
1665 
1666 /**
1667  * kernfs_remove_by_name_ns - find a kernfs_node by name and remove it
1668  * @parent: parent of the target
1669  * @name: name of the kernfs_node to remove
1670  * @ns: namespace tag of the kernfs_node to remove
1671  *
1672  * Look for the kernfs_node with @name and @ns under @parent and remove it.
1673  *
1674  * Return: %0 on success, -ENOENT if such entry doesn't exist.
1675  */
kernfs_remove_by_name_ns(struct kernfs_node * parent,const char * name,const void * ns)1676 int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
1677 			     const void *ns)
1678 {
1679 	struct kernfs_node *kn;
1680 	struct kernfs_root *root;
1681 
1682 	if (!parent) {
1683 		WARN(1, KERN_WARNING "kernfs: can not remove '%s', no directory\n",
1684 			name);
1685 		return -ENOENT;
1686 	}
1687 
1688 	root = kernfs_root(parent);
1689 	down_write(&root->kernfs_rwsem);
1690 
1691 	kn = kernfs_find_ns(parent, name, ns);
1692 	if (kn) {
1693 		kernfs_get(kn);
1694 		__kernfs_remove(kn);
1695 		kernfs_put(kn);
1696 	}
1697 
1698 	up_write(&root->kernfs_rwsem);
1699 
1700 	if (kn)
1701 		return 0;
1702 	else
1703 		return -ENOENT;
1704 }
1705 
1706 /**
1707  * kernfs_rename_ns - move and rename a kernfs_node
1708  * @kn: target node
1709  * @new_parent: new parent to put @sd under
1710  * @new_name: new name
1711  * @new_ns: new namespace tag
1712  *
1713  * Return: %0 on success, -errno on failure.
1714  */
kernfs_rename_ns(struct kernfs_node * kn,struct kernfs_node * new_parent,const char * new_name,const void * new_ns)1715 int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
1716 		     const char *new_name, const void *new_ns)
1717 {
1718 	struct kernfs_node *old_parent;
1719 	struct kernfs_root *root;
1720 	const char *old_name = NULL;
1721 	int error;
1722 
1723 	/* can't move or rename root */
1724 	if (!kn->parent)
1725 		return -EINVAL;
1726 
1727 	root = kernfs_root(kn);
1728 	down_write(&root->kernfs_rwsem);
1729 
1730 	error = -ENOENT;
1731 	if (!kernfs_active(kn) || !kernfs_active(new_parent) ||
1732 	    (new_parent->flags & KERNFS_EMPTY_DIR))
1733 		goto out;
1734 
1735 	error = 0;
1736 	if ((kn->parent == new_parent) && (kn->ns == new_ns) &&
1737 	    (strcmp(kn->name, new_name) == 0))
1738 		goto out;	/* nothing to rename */
1739 
1740 	error = -EEXIST;
1741 	if (kernfs_find_ns(new_parent, new_name, new_ns))
1742 		goto out;
1743 
1744 	/* rename kernfs_node */
1745 	if (strcmp(kn->name, new_name) != 0) {
1746 		error = -ENOMEM;
1747 		new_name = kstrdup_const(new_name, GFP_KERNEL);
1748 		if (!new_name)
1749 			goto out;
1750 	} else {
1751 		new_name = NULL;
1752 	}
1753 
1754 	/*
1755 	 * Move to the appropriate place in the appropriate directories rbtree.
1756 	 */
1757 	kernfs_unlink_sibling(kn);
1758 	kernfs_get(new_parent);
1759 
1760 	/* rename_lock protects ->parent and ->name accessors */
1761 	write_lock_irq(&kernfs_rename_lock);
1762 
1763 	old_parent = kn->parent;
1764 	kn->parent = new_parent;
1765 
1766 	kn->ns = new_ns;
1767 	if (new_name) {
1768 		old_name = kn->name;
1769 		kn->name = new_name;
1770 	}
1771 
1772 	write_unlock_irq(&kernfs_rename_lock);
1773 
1774 	kn->hash = kernfs_name_hash(kn->name, kn->ns);
1775 	kernfs_link_sibling(kn);
1776 
1777 	kernfs_put(old_parent);
1778 	kfree_const(old_name);
1779 
1780 	error = 0;
1781  out:
1782 	up_write(&root->kernfs_rwsem);
1783 	return error;
1784 }
1785 
kernfs_dir_fop_release(struct inode * inode,struct file * filp)1786 static int kernfs_dir_fop_release(struct inode *inode, struct file *filp)
1787 {
1788 	kernfs_put(filp->private_data);
1789 	return 0;
1790 }
1791 
kernfs_dir_pos(const void * ns,struct kernfs_node * parent,loff_t hash,struct kernfs_node * pos)1792 static struct kernfs_node *kernfs_dir_pos(const void *ns,
1793 	struct kernfs_node *parent, loff_t hash, struct kernfs_node *pos)
1794 {
1795 	if (pos) {
1796 		int valid = kernfs_active(pos) &&
1797 			pos->parent == parent && hash == pos->hash;
1798 		kernfs_put(pos);
1799 		if (!valid)
1800 			pos = NULL;
1801 	}
1802 	if (!pos && (hash > 1) && (hash < INT_MAX)) {
1803 		struct rb_node *node = parent->dir.children.rb_node;
1804 		while (node) {
1805 			pos = rb_to_kn(node);
1806 
1807 			if (hash < pos->hash)
1808 				node = node->rb_left;
1809 			else if (hash > pos->hash)
1810 				node = node->rb_right;
1811 			else
1812 				break;
1813 		}
1814 	}
1815 	/* Skip over entries which are dying/dead or in the wrong namespace */
1816 	while (pos && (!kernfs_active(pos) || pos->ns != ns)) {
1817 		struct rb_node *node = rb_next(&pos->rb);
1818 		if (!node)
1819 			pos = NULL;
1820 		else
1821 			pos = rb_to_kn(node);
1822 	}
1823 	return pos;
1824 }
1825 
kernfs_dir_next_pos(const void * ns,struct kernfs_node * parent,ino_t ino,struct kernfs_node * pos)1826 static struct kernfs_node *kernfs_dir_next_pos(const void *ns,
1827 	struct kernfs_node *parent, ino_t ino, struct kernfs_node *pos)
1828 {
1829 	pos = kernfs_dir_pos(ns, parent, ino, pos);
1830 	if (pos) {
1831 		do {
1832 			struct rb_node *node = rb_next(&pos->rb);
1833 			if (!node)
1834 				pos = NULL;
1835 			else
1836 				pos = rb_to_kn(node);
1837 		} while (pos && (!kernfs_active(pos) || pos->ns != ns));
1838 	}
1839 	return pos;
1840 }
1841 
kernfs_fop_readdir(struct file * file,struct dir_context * ctx)1842 static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx)
1843 {
1844 	struct dentry *dentry = file->f_path.dentry;
1845 	struct kernfs_node *parent = kernfs_dentry_node(dentry);
1846 	struct kernfs_node *pos = file->private_data;
1847 	struct kernfs_root *root;
1848 	const void *ns = NULL;
1849 
1850 	if (!dir_emit_dots(file, ctx))
1851 		return 0;
1852 
1853 	root = kernfs_root(parent);
1854 	down_read(&root->kernfs_rwsem);
1855 
1856 	if (kernfs_ns_enabled(parent))
1857 		ns = kernfs_info(dentry->d_sb)->ns;
1858 
1859 	for (pos = kernfs_dir_pos(ns, parent, ctx->pos, pos);
1860 	     pos;
1861 	     pos = kernfs_dir_next_pos(ns, parent, ctx->pos, pos)) {
1862 		const char *name = pos->name;
1863 		unsigned int type = fs_umode_to_dtype(pos->mode);
1864 		int len = strlen(name);
1865 		ino_t ino = kernfs_ino(pos);
1866 
1867 		ctx->pos = pos->hash;
1868 		file->private_data = pos;
1869 		kernfs_get(pos);
1870 
1871 		up_read(&root->kernfs_rwsem);
1872 		if (!dir_emit(ctx, name, len, ino, type))
1873 			return 0;
1874 		down_read(&root->kernfs_rwsem);
1875 	}
1876 	up_read(&root->kernfs_rwsem);
1877 	file->private_data = NULL;
1878 	ctx->pos = INT_MAX;
1879 	return 0;
1880 }
1881 
1882 const struct file_operations kernfs_dir_fops = {
1883 	.read		= generic_read_dir,
1884 	.iterate_shared	= kernfs_fop_readdir,
1885 	.release	= kernfs_dir_fop_release,
1886 	.llseek		= generic_file_llseek,
1887 };
1888