summaryrefslogtreecommitdiffstats
path: root/fs/sysfs/dir.c
blob: 61c42430cba3159e5cce02d8675cb2d8c1bec14b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
/*
 * dir.c - Operations for sysfs directories.
 */

#undef DEBUG

#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/module.h>
#include <linux/kobject.h>
#include <linux/namei.h>
#include "sysfs.h"

DECLARE_RWSEM(sysfs_rename_sem);

static void sysfs_d_iput(struct dentry * dentry, struct inode * inode)
{
	struct sysfs_dirent * sd = dentry->d_fsdata;

	if (sd) {
		BUG_ON(sd->s_dentry != dentry);
		sd->s_dentry = NULL;
		sysfs_put(sd);
	}
	iput(inode);
}

static struct dentry_operations sysfs_dentry_ops = {
	.d_iput		= sysfs_d_iput,
};

/*
 * Allocates a new sysfs_dirent and links it to the parent sysfs_dirent
 */
static struct sysfs_dirent * sysfs_new_dirent(struct sysfs_dirent * parent_sd,
						void * element)
{
	struct sysfs_dirent * sd;

	sd = kmem_cache_alloc(sysfs_dir_cachep, GFP_KERNEL);
	if (!sd)
		return NULL;

	memset(sd, 0, sizeof(*sd));
	atomic_set(&sd->s_count, 1);
	atomic_set(&sd->s_event, 0);
	INIT_LIST_HEAD(&sd->s_children);
	list_add(&sd->s_sibling, &parent_sd->s_children);
	sd->s_element = element;

	return sd;
}

/*
 *
 * Return -EEXIST if there is already a sysfs element with the same name for
 * the same parent.
 *
 * called with parent inode's i_mutex held
 */
int sysfs_dirent_exist(struct sysfs_dirent *parent_sd,
			  const unsigned char *new)
{
	struct sysfs_dirent * sd;

	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
		if (sd->s_element) {
			const unsigned char *existing = sysfs_get_name(sd);
			if (strcmp(existing, new))
				continue;
			else
				return -EEXIST;
		}
	}

	return 0;
}


int sysfs_make_dirent(struct sysfs_dirent * parent_sd, struct dentry * dentry,
			void * element, umode_t mode, int type)
{
	struct sysfs_dirent * sd;

	sd = sysfs_new_dirent(parent_sd, element);
	if (!sd)
		return -ENOMEM;

	sd->s_mode = mode;
	sd->s_type = type;
	sd->s_dentry = dentry;
	if (dentry) {
		dentry->d_fsdata = sysfs_get(sd);
		dentry->d_op = &sysfs_dentry_ops;
	}

	return 0;
}

static int init_dir(struct inode * inode)
{
	inode->i_op = &sysfs_dir_inode_operations;
	inode->i_fop = &sysfs_dir_operations;

	/* directory inodes start off with i_nlink == 2 (for "." entry) */
	inode->i_nlink++;
	return 0;
}

static int init_file(struct inode * inode)
{
	inode->i_size = PAGE_SIZE;
	inode->i_fop = &sysfs_file_operations;
	return 0;
}

static int init_symlink(struct inode * inode)
{
	inode->i_op = &sysfs_symlink_inode_operations;
	return 0;
}

static int create_dir(struct kobject * k, struct dentry * p,
		      const char * n, struct dentry ** d)
{
	int error;
	umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;

	mutex_lock(&p->d_inode->i_mutex);
	*d = lookup_one_len(n, p, strlen(n));
	if (!IS_ERR(*d)) {
 		if (sysfs_dirent_exist(p->d_fsdata, n))
  			error = -EEXIST;
  		else
			error = sysfs_make_dirent(p->d_fsdata, *d, k, mode,
								SYSFS_DIR);
		if (!error) {
			error = sysfs_create(*d, mode, init_dir);
			if (!error) {
				p->d_inode->i_nlink++;
				(*d)->d_op = &sysfs_dentry_ops;
				d_rehash(*d);
			}
		}
		if (error && (error != -EEXIST)) {
			struct sysfs_dirent *sd = (*d)->d_fsdata;
			if (sd) {
 				list_del_init(&sd->s_sibling);
				sysfs_put(sd);
			}
			d_drop(*d);
		}
		dput(*d);
	} else
		error = PTR_ERR(*d);
	mutex_unlock(&p->d_inode->i_mutex);
	return error;
}


int sysfs_create_subdir(struct kobject * k, const char * n, struct dentry ** d)
{
	return create_dir(k,k->dentry,n,d);
}

/**
 *	sysfs_create_dir - create a directory for an object.
 *	@parent:	parent parent object.
 *	@kobj:		object we're creating directory for. 
 */

int sysfs_create_dir(struct kobject * kobj)
{
	struct dentry * dentry = NULL;
	struct dentry * parent;
	int error = 0;

	BUG_ON(!kobj);

	if (kobj->parent)
		parent = kobj->parent->dentry;
	else if (sysfs_mount && sysfs_mount->mnt_sb)
		parent = sysfs_mount->mnt_sb->s_root;
	else
		return -EFAULT;

	error = create_dir(kobj,parent,kobject_name(kobj),&dentry);
	if (!error)
		kobj->dentry = dentry;
	return error;
}

/* attaches attribute's sysfs_dirent to the dentry corresponding to the
 * attribute file
 */
static int sysfs_attach_attr(struct sysfs_dirent * sd, struct dentry * dentry)
{
	struct attribute * attr = NULL;
	struct bin_attribute * bin_attr = NULL;
	int (* init) (struct inode *) = NULL;
	int error = 0;

        if (sd->s_type & SYSFS_KOBJ_BIN_ATTR) {
                bin_attr = sd->s_element;
                attr = &bin_attr->attr;
        } else {
                attr = sd->s_element;
                init = init_file;
        }

	dentry->d_fsdata = sysfs_get(sd);
	sd->s_dentry = dentry;
	error = sysfs_create(dentry, (attr->mode & S_IALLUGO) | S_IFREG, init);
	if (error) {
		sysfs_put(sd);
		return error;
	}

        if (bin_attr) {
		dentry->d_inode->i_size = bin_attr->size;
		dentry->d_inode->i_fop = &bin_fops;
	}
	dentry->d_op = &sysfs_dentry_ops;
	d_rehash(dentry);

	return 0;
}

static int sysfs_attach_link(struct sysfs_dirent * sd, struct dentry * dentry)
{
	int err = 0;

	dentry->d_fsdata = sysfs_get(sd);
	sd->s_dentry = dentry;
	err = sysfs_create(dentry, S_IFLNK|S_IRWXUGO, init_symlink);
	if (!err) {
		dentry->d_op = &sysfs_dentry_ops;
		d_rehash(dentry);
	} else
		sysfs_put(sd);

	return err;
}

static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
				struct nameidata *nd)
{
	struct sysfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
	struct sysfs_dirent * sd;
	int err = 0;

	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
		if (sd->s_type & SYSFS_NOT_PINNED) {
			const unsigned char * name = sysfs_get_name(sd);

			if (strcmp(name, dentry->d_name.name))
				continue;

			if (sd->s_type & SYSFS_KOBJ_LINK)
				err = sysfs_attach_link(sd, dentry);
			else
				err = sysfs_attach_attr(sd, dentry);
			break;
		}
	}

	return ERR_PTR(err);
}

struct inode_operations sysfs_dir_inode_operations = {
	.lookup		= sysfs_lookup,
	.setattr	= sysfs_setattr,
};

static void remove_dir(struct dentry * d)
{
	struct dentry * parent = dget(d->d_parent);
	struct sysfs_dirent * sd;

	mutex_lock(&parent->d_inode->i_mutex);
	d_delete(d);
	sd = d->d_fsdata;
 	list_del_init(&sd->s_sibling);
	sysfs_put(sd);
	if (d->d_inode)
		simple_rmdir(parent->d_inode,d);

	pr_debug(" o %s removing done (%d)\n",d->d_name.name,
		 atomic_read(&d->d_count));

	mutex_unlock(&parent->d_inode->i_mutex);
	dput(parent);
}

void sysfs_remove_subdir(struct dentry * d)
{
	remove_dir(d);
}


/**
 *	sysfs_remove_dir - remove an object's directory.
 *	@kobj:	object. 
 *
 *	The only thing special about this is that we remove any files in 
 *	the directory before we remove the directory, and we've inlined
 *	what used to be sysfs_rmdir() below, instead of calling separately.
 */

void sysfs_remove_dir(struct kobject * kobj)
{
	struct dentry * dentry = dget(kobj->dentry);
	struct sysfs_dirent * parent_sd;
	struct sysfs_dirent * sd, * tmp;

	if (!dentry)
		return;

	pr_debug("sysfs %s: removing dir\n",dentry->d_name.name);
	mutex_lock(&dentry->d_inode->i_mutex);
	parent_sd = dentry->d_fsdata;
	list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
		if (!sd->s_element || !(sd->s_type & SYSFS_NOT_PINNED))
			continue;
		list_del_init(&sd->s_sibling);
		sysfs_drop_dentry(sd, dentry);
		sysfs_put(sd);
	}
	mutex_unlock(&dentry->d_inode->i_mutex);

	remove_dir(dentry);
	/**
	 * Drop reference from dget() on entrance.
	 */
	dput(dentry);
	kobj->dentry = NULL;
}

int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
{
	int error = 0;
	struct dentry * new_dentry, * parent;

	if (!strcmp(kobject_name(kobj), new_name))
		return -EINVAL;

	if (!kobj->parent)
		return -EINVAL;

	down_write(&sysfs_rename_sem);
	parent = kobj->parent->dentry;

	mutex_lock(&parent->d_inode->i_mutex);

	new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
	if (!IS_ERR(new_dentry)) {
  		if (!new_dentry->d_inode) {
			error = kobject_set_name(kobj, "%s", new_name);
			if (!error) {
				d_add(new_dentry, NULL);
				d_move(kobj->dentry, new_dentry);
			}
			else
				d_drop(new_dentry);
		} else
			error = -EEXIST;
		dput(new_dentry);
	}
	mutex_unlock(&parent->d_inode->i_mutex);
	up_write(&sysfs_rename_sem);

	return error;
}

static int sysfs_dir_open(struct inode *inode, struct file *file)
{
	struct dentry * dentry = file->f_dentry;
	struct sysfs_dirent * parent_sd = dentry->d_fsdata;

	mutex_lock(&dentry->d_inode->i_mutex);
	file->private_data = sysfs_new_dirent(parent_sd, NULL);
	mutex_unlock(&dentry->d_inode->i_mutex);

	return file->private_data ? 0 : -ENOMEM;

}

static int sysfs_dir_close(struct inode *inode, struct file *file)
{
	struct dentry * dentry = file->f_dentry;
	struct sysfs_dirent * cursor = file->private_data;

	mutex_lock(&dentry->d_inode->i_mutex);
	list_del_init(&cursor->s_sibling);
	mutex_unlock(&dentry->d_inode->i_mutex);

	release_sysfs_dirent(cursor);

	return 0;
}

/* Relationship between s_mode and the DT_xxx types */
static inline unsigned char dt_type(struct sysfs_dirent *sd)
{
	return (sd->s_mode >> 12) & 15;
}

static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
	struct dentry *dentry = filp->f_dentry;
	struct sysfs_dirent * parent_sd = dentry->d_fsdata;
	struct sysfs_dirent *cursor = filp->private_data;
	struct list_head *p, *q = &cursor->s_sibling;
	ino_t ino;
	int i = filp->f_pos;

	switch (i) {
		case 0:
			ino = dentry->d_inode->i_ino;
			if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
				break;
			filp->f_pos++;
			i++;
			/* fallthrough */
		case 1:
			ino = parent_ino(dentry);
			if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
				break;
			filp->f_pos++;
			i++;
			/* fallthrough */
		default:
			if (filp->f_pos == 2)
				list_move(q, &parent_sd->s_children);

			for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
				struct sysfs_dirent *next;
				const char * name;
				int len;

				next = list_entry(p, struct sysfs_dirent,
						   s_sibling);
				if (!next->s_element)
					continue;

				name = sysfs_get_name(next);
				len = strlen(name);
				if (next->s_dentry)
					ino = next->s_dentry->d_inode->i_ino;
				else
					ino = iunique(sysfs_sb, 2);

				if (filldir(dirent, name, len, filp->f_pos, ino,
						 dt_type(next)) < 0)
					return 0;

				list_move(q, p);
				p = q;
				filp->f_pos++;
			}
	}
	return 0;
}

static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
{
	struct dentry * dentry = file->f_dentry;

	mutex_lock(&dentry->d_inode->i_mutex);
	switch (origin) {
		case 1:
			offset += file->f_pos;
		case 0:
			if (offset >= 0)
				break;
		default:
			mutex_unlock(&file->f_dentry->d_inode->i_mutex);
			return -EINVAL;
	}
	if (offset != file->f_pos) {
		file->f_pos = offset;
		if (file->f_pos >= 2) {
			struct sysfs_dirent *sd = dentry->d_fsdata;
			struct sysfs_dirent *cursor = file->private_data;
			struct list_head *p;
			loff_t n = file->f_pos - 2;

			list_del(&cursor->s_sibling);
			p = sd->s_children.next;
			while (n && p != &sd->s_children) {
				struct sysfs_dirent *next;
				next = list_entry(p, struct sysfs_dirent,
						   s_sibling);
				if (next->s_element)
					n--;
				p = p->next;
			}
			list_add_tail(&cursor->s_sibling, p);
		}
	}
	mutex_unlock(&dentry->d_inode->i_mutex);
	return offset;
}

const struct file_operations sysfs_dir_operations = {
	.open		= sysfs_dir_open,
	.release	= sysfs_dir_close,
	.llseek		= sysfs_dir_lseek,
	.read		= generic_read_dir,
	.readdir	= sysfs_readdir,
};