summaryrefslogtreecommitdiffstats
path: root/fs/sysfs/inode.c
blob: aff7b2dfa8eed3a4c4c76b81cfffd26f04344706 (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
/*
 * inode.c - basic inode and dentry operations.
 *
 * sysfs is Copyright (c) 2001-3 Patrick Mochel
 *
 * Please see Documentation/filesystems/sysfs.txt for more information.
 */

#undef DEBUG 

#include <linux/pagemap.h>
#include <linux/namei.h>
#include <linux/backing-dev.h>
#include "sysfs.h"

extern struct super_block * sysfs_sb;

static struct address_space_operations sysfs_aops = {
	.readpage	= simple_readpage,
	.prepare_write	= simple_prepare_write,
	.commit_write	= simple_commit_write
};

static struct backing_dev_info sysfs_backing_dev_info = {
	.ra_pages	= 0,	/* No readahead */
	.capabilities	= BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
};

struct inode * sysfs_new_inode(mode_t mode)
{
	struct inode * inode = new_inode(sysfs_sb);
	if (inode) {
		inode->i_mode = mode;
		inode->i_uid = 0;
		inode->i_gid = 0;
		inode->i_blksize = PAGE_CACHE_SIZE;
		inode->i_blocks = 0;
		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
		inode->i_mapping->a_ops = &sysfs_aops;
		inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
	}
	return inode;
}

int sysfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
{
	int error = 0;
	struct inode * inode = NULL;
	if (dentry) {
		if (!dentry->d_inode) {
			if ((inode = sysfs_new_inode(mode))) {
				if (dentry->d_parent && dentry->d_parent->d_inode) {
					struct inode *p_inode = dentry->d_parent->d_inode;
					p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
				}
				goto Proceed;
			}
			else 
				error = -ENOMEM;
		} else
			error = -EEXIST;
	} else 
		error = -ENOENT;
	goto Done;

 Proceed:
	if (init)
		error = init(inode);
	if (!error) {
		d_instantiate(dentry, inode);
		if (S_ISDIR(mode))
			dget(dentry);  /* pin only directory dentry in core */
	} else
		iput(inode);
 Done:
	return error;
}

struct dentry * sysfs_get_dentry(struct dentry * parent, const char * name)
{
	struct qstr qstr;

	qstr.name = name;
	qstr.len = strlen(name);
	qstr.hash = full_name_hash(name,qstr.len);
	return lookup_hash(&qstr,parent);
}

/*
 * Get the name for corresponding element represented by the given sysfs_dirent
 */
const unsigned char * sysfs_get_name(struct sysfs_dirent *sd)
{
	struct attribute * attr;
	struct bin_attribute * bin_attr;
	struct sysfs_symlink  * sl;

	if (!sd || !sd->s_element)
		BUG();

	switch (sd->s_type) {
		case SYSFS_DIR:
			/* Always have a dentry so use that */
			return sd->s_dentry->d_name.name;

		case SYSFS_KOBJ_ATTR:
			attr = sd->s_element;
			return attr->name;

		case SYSFS_KOBJ_BIN_ATTR:
			bin_attr = sd->s_element;
			return bin_attr->attr.name;

		case SYSFS_KOBJ_LINK:
			sl = sd->s_element;
			return sl->link_name;
	}
	return NULL;
}


/*
 * Unhashes the dentry corresponding to given sysfs_dirent
 * Called with parent inode's i_sem held.
 */
void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent)
{
	struct dentry * dentry = sd->s_dentry;

	if (dentry) {
		spin_lock(&dcache_lock);
		spin_lock(&dentry->d_lock);
		if (!(d_unhashed(dentry) && dentry->d_inode)) {
			dget_locked(dentry);
			__d_drop(dentry);
			spin_unlock(&dentry->d_lock);
			spin_unlock(&dcache_lock);
			simple_unlink(parent->d_inode, dentry);
		} else {
			spin_unlock(&dentry->d_lock);
			spin_unlock(&dcache_lock);
		}
	}
}

void sysfs_hash_and_remove(struct dentry * dir, const char * name)
{
	struct sysfs_dirent * sd;
	struct sysfs_dirent * parent_sd = dir->d_fsdata;

	down(&dir->d_inode->i_sem);
	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
		if (!sd->s_element)
			continue;
		if (!strcmp(sysfs_get_name(sd), name)) {
			list_del_init(&sd->s_sibling);
			sysfs_drop_dentry(sd, dir);
			sysfs_put(sd);
			break;
		}
	}
	up(&dir->d_inode->i_sem);
}