xref: /openbmc/linux/fs/sysfs/dir.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  * dir.c - Operations for sysfs directories.
3  */
4 
5 #undef DEBUG
6 
7 #include <linux/fs.h>
8 #include <linux/mount.h>
9 #include <linux/module.h>
10 #include <linux/kobject.h>
11 #include <linux/namei.h>
12 #include <asm/semaphore.h>
13 #include "sysfs.h"
14 
15 DECLARE_RWSEM(sysfs_rename_sem);
16 
17 static void sysfs_d_iput(struct dentry * dentry, struct inode * inode)
18 {
19 	struct sysfs_dirent * sd = dentry->d_fsdata;
20 
21 	if (sd) {
22 		BUG_ON(sd->s_dentry != dentry);
23 		sd->s_dentry = NULL;
24 		sysfs_put(sd);
25 	}
26 	iput(inode);
27 }
28 
29 static struct dentry_operations sysfs_dentry_ops = {
30 	.d_iput		= sysfs_d_iput,
31 };
32 
33 /*
34  * Allocates a new sysfs_dirent and links it to the parent sysfs_dirent
35  */
36 static struct sysfs_dirent * __sysfs_new_dirent(void * element)
37 {
38 	struct sysfs_dirent * sd;
39 
40 	sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
41 	if (!sd)
42 		return NULL;
43 
44 	atomic_set(&sd->s_count, 1);
45 	atomic_set(&sd->s_event, 1);
46 	INIT_LIST_HEAD(&sd->s_children);
47 	INIT_LIST_HEAD(&sd->s_sibling);
48 	sd->s_element = element;
49 
50 	return sd;
51 }
52 
53 static void __sysfs_list_dirent(struct sysfs_dirent *parent_sd,
54 			      struct sysfs_dirent *sd)
55 {
56 	if (sd)
57 		list_add(&sd->s_sibling, &parent_sd->s_children);
58 }
59 
60 static struct sysfs_dirent * sysfs_new_dirent(struct sysfs_dirent *parent_sd,
61 						void * element)
62 {
63 	struct sysfs_dirent *sd;
64 	sd = __sysfs_new_dirent(element);
65 	__sysfs_list_dirent(parent_sd, sd);
66 	return sd;
67 }
68 
69 /*
70  *
71  * Return -EEXIST if there is already a sysfs element with the same name for
72  * the same parent.
73  *
74  * called with parent inode's i_mutex held
75  */
76 int sysfs_dirent_exist(struct sysfs_dirent *parent_sd,
77 			  const unsigned char *new)
78 {
79 	struct sysfs_dirent * sd;
80 
81 	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
82 		if (sd->s_element) {
83 			const unsigned char *existing = sysfs_get_name(sd);
84 			if (strcmp(existing, new))
85 				continue;
86 			else
87 				return -EEXIST;
88 		}
89 	}
90 
91 	return 0;
92 }
93 
94 
95 static struct sysfs_dirent *
96 __sysfs_make_dirent(struct dentry *dentry, void *element, mode_t mode, int type)
97 {
98 	struct sysfs_dirent * sd;
99 
100 	sd = __sysfs_new_dirent(element);
101 	if (!sd)
102 		goto out;
103 
104 	sd->s_mode = mode;
105 	sd->s_type = type;
106 	sd->s_dentry = dentry;
107 	if (dentry) {
108 		dentry->d_fsdata = sysfs_get(sd);
109 		dentry->d_op = &sysfs_dentry_ops;
110 	}
111 
112 out:
113 	return sd;
114 }
115 
116 int sysfs_make_dirent(struct sysfs_dirent * parent_sd, struct dentry * dentry,
117 			void * element, umode_t mode, int type)
118 {
119 	struct sysfs_dirent *sd;
120 
121 	sd = __sysfs_make_dirent(dentry, element, mode, type);
122 	__sysfs_list_dirent(parent_sd, sd);
123 
124 	return sd ? 0 : -ENOMEM;
125 }
126 
127 static int init_dir(struct inode * inode)
128 {
129 	inode->i_op = &sysfs_dir_inode_operations;
130 	inode->i_fop = &sysfs_dir_operations;
131 
132 	/* directory inodes start off with i_nlink == 2 (for "." entry) */
133 	inc_nlink(inode);
134 	return 0;
135 }
136 
137 static int init_file(struct inode * inode)
138 {
139 	inode->i_size = PAGE_SIZE;
140 	inode->i_fop = &sysfs_file_operations;
141 	return 0;
142 }
143 
144 static int init_symlink(struct inode * inode)
145 {
146 	inode->i_op = &sysfs_symlink_inode_operations;
147 	return 0;
148 }
149 
150 static int create_dir(struct kobject * k, struct dentry * p,
151 		      const char * n, struct dentry ** d)
152 {
153 	int error;
154 	umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
155 
156 	mutex_lock(&p->d_inode->i_mutex);
157 	*d = lookup_one_len(n, p, strlen(n));
158 	if (!IS_ERR(*d)) {
159  		if (sysfs_dirent_exist(p->d_fsdata, n))
160   			error = -EEXIST;
161   		else
162 			error = sysfs_make_dirent(p->d_fsdata, *d, k, mode,
163 								SYSFS_DIR);
164 		if (!error) {
165 			error = sysfs_create(*d, mode, init_dir);
166 			if (!error) {
167 				inc_nlink(p->d_inode);
168 				(*d)->d_op = &sysfs_dentry_ops;
169 				d_rehash(*d);
170 			}
171 		}
172 		if (error && (error != -EEXIST)) {
173 			struct sysfs_dirent *sd = (*d)->d_fsdata;
174 			if (sd) {
175  				list_del_init(&sd->s_sibling);
176 				sysfs_put(sd);
177 			}
178 			d_drop(*d);
179 		}
180 		dput(*d);
181 	} else
182 		error = PTR_ERR(*d);
183 	mutex_unlock(&p->d_inode->i_mutex);
184 	return error;
185 }
186 
187 
188 int sysfs_create_subdir(struct kobject * k, const char * n, struct dentry ** d)
189 {
190 	return create_dir(k,k->dentry,n,d);
191 }
192 
193 /**
194  *	sysfs_create_dir - create a directory for an object.
195  *	@kobj:		object we're creating directory for.
196  *	@shadow_parent:	parent parent object.
197  */
198 
199 int sysfs_create_dir(struct kobject * kobj, struct dentry *shadow_parent)
200 {
201 	struct dentry * dentry = NULL;
202 	struct dentry * parent;
203 	int error = 0;
204 
205 	BUG_ON(!kobj);
206 
207 	if (shadow_parent)
208 		parent = shadow_parent;
209 	else if (kobj->parent)
210 		parent = kobj->parent->dentry;
211 	else if (sysfs_mount && sysfs_mount->mnt_sb)
212 		parent = sysfs_mount->mnt_sb->s_root;
213 	else
214 		return -EFAULT;
215 
216 	error = create_dir(kobj,parent,kobject_name(kobj),&dentry);
217 	if (!error)
218 		kobj->dentry = dentry;
219 	return error;
220 }
221 
222 /* attaches attribute's sysfs_dirent to the dentry corresponding to the
223  * attribute file
224  */
225 static int sysfs_attach_attr(struct sysfs_dirent * sd, struct dentry * dentry)
226 {
227 	struct attribute * attr = NULL;
228 	struct bin_attribute * bin_attr = NULL;
229 	int (* init) (struct inode *) = NULL;
230 	int error = 0;
231 
232         if (sd->s_type & SYSFS_KOBJ_BIN_ATTR) {
233                 bin_attr = sd->s_element;
234                 attr = &bin_attr->attr;
235         } else {
236                 attr = sd->s_element;
237                 init = init_file;
238         }
239 
240 	dentry->d_fsdata = sysfs_get(sd);
241 	sd->s_dentry = dentry;
242 	error = sysfs_create(dentry, (attr->mode & S_IALLUGO) | S_IFREG, init);
243 	if (error) {
244 		sysfs_put(sd);
245 		return error;
246 	}
247 
248         if (bin_attr) {
249 		dentry->d_inode->i_size = bin_attr->size;
250 		dentry->d_inode->i_fop = &bin_fops;
251 	}
252 	dentry->d_op = &sysfs_dentry_ops;
253 	d_rehash(dentry);
254 
255 	return 0;
256 }
257 
258 static int sysfs_attach_link(struct sysfs_dirent * sd, struct dentry * dentry)
259 {
260 	int err = 0;
261 
262 	dentry->d_fsdata = sysfs_get(sd);
263 	sd->s_dentry = dentry;
264 	err = sysfs_create(dentry, S_IFLNK|S_IRWXUGO, init_symlink);
265 	if (!err) {
266 		dentry->d_op = &sysfs_dentry_ops;
267 		d_rehash(dentry);
268 	} else
269 		sysfs_put(sd);
270 
271 	return err;
272 }
273 
274 static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
275 				struct nameidata *nd)
276 {
277 	struct sysfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
278 	struct sysfs_dirent * sd;
279 	int err = 0;
280 
281 	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
282 		if (sd->s_type & SYSFS_NOT_PINNED) {
283 			const unsigned char * name = sysfs_get_name(sd);
284 
285 			if (strcmp(name, dentry->d_name.name))
286 				continue;
287 
288 			if (sd->s_type & SYSFS_KOBJ_LINK)
289 				err = sysfs_attach_link(sd, dentry);
290 			else
291 				err = sysfs_attach_attr(sd, dentry);
292 			break;
293 		}
294 	}
295 
296 	return ERR_PTR(err);
297 }
298 
299 const struct inode_operations sysfs_dir_inode_operations = {
300 	.lookup		= sysfs_lookup,
301 	.setattr	= sysfs_setattr,
302 };
303 
304 static void remove_dir(struct dentry * d)
305 {
306 	struct dentry * parent = dget(d->d_parent);
307 	struct sysfs_dirent * sd;
308 
309 	mutex_lock(&parent->d_inode->i_mutex);
310 	d_delete(d);
311 	sd = d->d_fsdata;
312  	list_del_init(&sd->s_sibling);
313 	sysfs_put(sd);
314 	if (d->d_inode)
315 		simple_rmdir(parent->d_inode,d);
316 
317 	pr_debug(" o %s removing done (%d)\n",d->d_name.name,
318 		 atomic_read(&d->d_count));
319 
320 	mutex_unlock(&parent->d_inode->i_mutex);
321 	dput(parent);
322 }
323 
324 void sysfs_remove_subdir(struct dentry * d)
325 {
326 	remove_dir(d);
327 }
328 
329 
330 static void __sysfs_remove_dir(struct dentry *dentry)
331 {
332 	struct sysfs_dirent * parent_sd;
333 	struct sysfs_dirent * sd, * tmp;
334 
335 	dget(dentry);
336 	if (!dentry)
337 		return;
338 
339 	pr_debug("sysfs %s: removing dir\n",dentry->d_name.name);
340 	mutex_lock(&dentry->d_inode->i_mutex);
341 	parent_sd = dentry->d_fsdata;
342 	list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
343 		if (!sd->s_element || !(sd->s_type & SYSFS_NOT_PINNED))
344 			continue;
345 		list_del_init(&sd->s_sibling);
346 		sysfs_drop_dentry(sd, dentry);
347 		sysfs_put(sd);
348 	}
349 	mutex_unlock(&dentry->d_inode->i_mutex);
350 
351 	remove_dir(dentry);
352 	/**
353 	 * Drop reference from dget() on entrance.
354 	 */
355 	dput(dentry);
356 }
357 
358 /**
359  *	sysfs_remove_dir - remove an object's directory.
360  *	@kobj:	object.
361  *
362  *	The only thing special about this is that we remove any files in
363  *	the directory before we remove the directory, and we've inlined
364  *	what used to be sysfs_rmdir() below, instead of calling separately.
365  */
366 
367 void sysfs_remove_dir(struct kobject * kobj)
368 {
369 	__sysfs_remove_dir(kobj->dentry);
370 	kobj->dentry = NULL;
371 }
372 
373 int sysfs_rename_dir(struct kobject * kobj, struct dentry *new_parent,
374 		     const char *new_name)
375 {
376 	int error = 0;
377 	struct dentry * new_dentry;
378 
379 	if (!new_parent)
380 		return -EFAULT;
381 
382 	down_write(&sysfs_rename_sem);
383 	mutex_lock(&new_parent->d_inode->i_mutex);
384 
385 	new_dentry = lookup_one_len(new_name, new_parent, strlen(new_name));
386 	if (!IS_ERR(new_dentry)) {
387 		/* By allowing two different directories with the
388 		 * same d_parent we allow this routine to move
389 		 * between different shadows of the same directory
390 		 */
391 		if (kobj->dentry->d_parent->d_inode != new_parent->d_inode)
392 			return -EINVAL;
393 		else if (new_dentry->d_parent->d_inode != new_parent->d_inode)
394 			error = -EINVAL;
395 		else if (new_dentry == kobj->dentry)
396 			error = -EINVAL;
397 		else if (!new_dentry->d_inode) {
398 			error = kobject_set_name(kobj, "%s", new_name);
399 			if (!error) {
400 				struct sysfs_dirent *sd, *parent_sd;
401 
402 				d_add(new_dentry, NULL);
403 				d_move(kobj->dentry, new_dentry);
404 
405 				sd = kobj->dentry->d_fsdata;
406 				parent_sd = new_parent->d_fsdata;
407 
408 				list_del_init(&sd->s_sibling);
409 				list_add(&sd->s_sibling, &parent_sd->s_children);
410 			}
411 			else
412 				d_drop(new_dentry);
413 		} else
414 			error = -EEXIST;
415 		dput(new_dentry);
416 	}
417 	mutex_unlock(&new_parent->d_inode->i_mutex);
418 	up_write(&sysfs_rename_sem);
419 
420 	return error;
421 }
422 
423 int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent)
424 {
425 	struct dentry *old_parent_dentry, *new_parent_dentry, *new_dentry;
426 	struct sysfs_dirent *new_parent_sd, *sd;
427 	int error;
428 
429 	old_parent_dentry = kobj->parent ?
430 		kobj->parent->dentry : sysfs_mount->mnt_sb->s_root;
431 	new_parent_dentry = new_parent ?
432 		new_parent->dentry : sysfs_mount->mnt_sb->s_root;
433 
434 	if (old_parent_dentry->d_inode == new_parent_dentry->d_inode)
435 		return 0;	/* nothing to move */
436 again:
437 	mutex_lock(&old_parent_dentry->d_inode->i_mutex);
438 	if (!mutex_trylock(&new_parent_dentry->d_inode->i_mutex)) {
439 		mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
440 		goto again;
441 	}
442 
443 	new_parent_sd = new_parent_dentry->d_fsdata;
444 	sd = kobj->dentry->d_fsdata;
445 
446 	new_dentry = lookup_one_len(kobj->name, new_parent_dentry,
447 				    strlen(kobj->name));
448 	if (IS_ERR(new_dentry)) {
449 		error = PTR_ERR(new_dentry);
450 		goto out;
451 	} else
452 		error = 0;
453 	d_add(new_dentry, NULL);
454 	d_move(kobj->dentry, new_dentry);
455 	dput(new_dentry);
456 
457 	/* Remove from old parent's list and insert into new parent's list. */
458 	list_del_init(&sd->s_sibling);
459 	list_add(&sd->s_sibling, &new_parent_sd->s_children);
460 
461 out:
462 	mutex_unlock(&new_parent_dentry->d_inode->i_mutex);
463 	mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
464 
465 	return error;
466 }
467 
468 static int sysfs_dir_open(struct inode *inode, struct file *file)
469 {
470 	struct dentry * dentry = file->f_path.dentry;
471 	struct sysfs_dirent * parent_sd = dentry->d_fsdata;
472 
473 	mutex_lock(&dentry->d_inode->i_mutex);
474 	file->private_data = sysfs_new_dirent(parent_sd, NULL);
475 	mutex_unlock(&dentry->d_inode->i_mutex);
476 
477 	return file->private_data ? 0 : -ENOMEM;
478 
479 }
480 
481 static int sysfs_dir_close(struct inode *inode, struct file *file)
482 {
483 	struct dentry * dentry = file->f_path.dentry;
484 	struct sysfs_dirent * cursor = file->private_data;
485 
486 	mutex_lock(&dentry->d_inode->i_mutex);
487 	list_del_init(&cursor->s_sibling);
488 	mutex_unlock(&dentry->d_inode->i_mutex);
489 
490 	release_sysfs_dirent(cursor);
491 
492 	return 0;
493 }
494 
495 /* Relationship between s_mode and the DT_xxx types */
496 static inline unsigned char dt_type(struct sysfs_dirent *sd)
497 {
498 	return (sd->s_mode >> 12) & 15;
499 }
500 
501 static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
502 {
503 	struct dentry *dentry = filp->f_path.dentry;
504 	struct sysfs_dirent * parent_sd = dentry->d_fsdata;
505 	struct sysfs_dirent *cursor = filp->private_data;
506 	struct list_head *p, *q = &cursor->s_sibling;
507 	ino_t ino;
508 	int i = filp->f_pos;
509 
510 	switch (i) {
511 		case 0:
512 			ino = dentry->d_inode->i_ino;
513 			if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
514 				break;
515 			filp->f_pos++;
516 			i++;
517 			/* fallthrough */
518 		case 1:
519 			ino = parent_ino(dentry);
520 			if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
521 				break;
522 			filp->f_pos++;
523 			i++;
524 			/* fallthrough */
525 		default:
526 			if (filp->f_pos == 2)
527 				list_move(q, &parent_sd->s_children);
528 
529 			for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
530 				struct sysfs_dirent *next;
531 				const char * name;
532 				int len;
533 
534 				next = list_entry(p, struct sysfs_dirent,
535 						   s_sibling);
536 				if (!next->s_element)
537 					continue;
538 
539 				name = sysfs_get_name(next);
540 				len = strlen(name);
541 				if (next->s_dentry)
542 					ino = next->s_dentry->d_inode->i_ino;
543 				else
544 					ino = iunique(sysfs_sb, 2);
545 
546 				if (filldir(dirent, name, len, filp->f_pos, ino,
547 						 dt_type(next)) < 0)
548 					return 0;
549 
550 				list_move(q, p);
551 				p = q;
552 				filp->f_pos++;
553 			}
554 	}
555 	return 0;
556 }
557 
558 static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
559 {
560 	struct dentry * dentry = file->f_path.dentry;
561 
562 	mutex_lock(&dentry->d_inode->i_mutex);
563 	switch (origin) {
564 		case 1:
565 			offset += file->f_pos;
566 		case 0:
567 			if (offset >= 0)
568 				break;
569 		default:
570 			mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
571 			return -EINVAL;
572 	}
573 	if (offset != file->f_pos) {
574 		file->f_pos = offset;
575 		if (file->f_pos >= 2) {
576 			struct sysfs_dirent *sd = dentry->d_fsdata;
577 			struct sysfs_dirent *cursor = file->private_data;
578 			struct list_head *p;
579 			loff_t n = file->f_pos - 2;
580 
581 			list_del(&cursor->s_sibling);
582 			p = sd->s_children.next;
583 			while (n && p != &sd->s_children) {
584 				struct sysfs_dirent *next;
585 				next = list_entry(p, struct sysfs_dirent,
586 						   s_sibling);
587 				if (next->s_element)
588 					n--;
589 				p = p->next;
590 			}
591 			list_add_tail(&cursor->s_sibling, p);
592 		}
593 	}
594 	mutex_unlock(&dentry->d_inode->i_mutex);
595 	return offset;
596 }
597 
598 
599 /**
600  *	sysfs_make_shadowed_dir - Setup so a directory can be shadowed
601  *	@kobj:	object we're creating shadow of.
602  */
603 
604 int sysfs_make_shadowed_dir(struct kobject *kobj,
605 	void * (*follow_link)(struct dentry *, struct nameidata *))
606 {
607 	struct inode *inode;
608 	struct inode_operations *i_op;
609 
610 	inode = kobj->dentry->d_inode;
611 	if (inode->i_op != &sysfs_dir_inode_operations)
612 		return -EINVAL;
613 
614 	i_op = kmalloc(sizeof(*i_op), GFP_KERNEL);
615 	if (!i_op)
616 		return -ENOMEM;
617 
618 	memcpy(i_op, &sysfs_dir_inode_operations, sizeof(*i_op));
619 	i_op->follow_link = follow_link;
620 
621 	/* Locking of inode->i_op?
622 	 * Since setting i_op is a single word write and they
623 	 * are atomic we should be ok here.
624 	 */
625 	inode->i_op = i_op;
626 	return 0;
627 }
628 
629 /**
630  *	sysfs_create_shadow_dir - create a shadow directory for an object.
631  *	@kobj:	object we're creating directory for.
632  *
633  *	sysfs_make_shadowed_dir must already have been called on this
634  *	directory.
635  */
636 
637 struct dentry *sysfs_create_shadow_dir(struct kobject *kobj)
638 {
639 	struct sysfs_dirent *sd;
640 	struct dentry *parent, *dir, *shadow;
641 	struct inode *inode;
642 
643 	dir = kobj->dentry;
644 	inode = dir->d_inode;
645 	parent = dir->d_parent;
646 	shadow = ERR_PTR(-EINVAL);
647 	if (!sysfs_is_shadowed_inode(inode))
648 		goto out;
649 
650 	shadow = d_alloc(parent, &dir->d_name);
651 	if (!shadow)
652 		goto nomem;
653 
654 	sd = __sysfs_make_dirent(shadow, kobj, inode->i_mode, SYSFS_DIR);
655 	if (!sd)
656 		goto nomem;
657 
658 	d_instantiate(shadow, igrab(inode));
659 	inc_nlink(inode);
660 	inc_nlink(parent->d_inode);
661 	shadow->d_op = &sysfs_dentry_ops;
662 
663 	dget(shadow);		/* Extra count - pin the dentry in core */
664 
665 out:
666 	return shadow;
667 nomem:
668 	dput(shadow);
669 	shadow = ERR_PTR(-ENOMEM);
670 	goto out;
671 }
672 
673 /**
674  *	sysfs_remove_shadow_dir - remove an object's directory.
675  *	@shadow: dentry of shadow directory
676  *
677  *	The only thing special about this is that we remove any files in
678  *	the directory before we remove the directory, and we've inlined
679  *	what used to be sysfs_rmdir() below, instead of calling separately.
680  */
681 
682 void sysfs_remove_shadow_dir(struct dentry *shadow)
683 {
684 	__sysfs_remove_dir(shadow);
685 }
686 
687 const struct file_operations sysfs_dir_operations = {
688 	.open		= sysfs_dir_open,
689 	.release	= sysfs_dir_close,
690 	.llseek		= sysfs_dir_lseek,
691 	.read		= generic_read_dir,
692 	.readdir	= sysfs_readdir,
693 };
694