[mirror_ubuntu-eoan-kernel.git] / fs / sysfs / inode.c

/*
 * 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 <linux/capability.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <asm/semaphore.h>
#include "sysfs.h"

extern struct super_block * sysfs_sb;

static const 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,
};

static const struct inode_operations sysfs_inode_operations ={
	.setattr	= sysfs_setattr,
};

void sysfs_delete_inode(struct inode *inode)
{
	/* Free the shadowed directory inode operations */
	if (sysfs_is_shadowed_inode(inode)) {
		kfree(inode->i_op);
		inode->i_op = NULL;
	}
	return generic_delete_inode(inode);
}

int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
{
	struct inode * inode = dentry->d_inode;
	struct sysfs_dirent * sd = dentry->d_fsdata;
	struct iattr * sd_iattr;
	unsigned int ia_valid = iattr->ia_valid;
	int error;

	if (!sd)
		return -EINVAL;

	sd_iattr = sd->s_iattr;

	error = inode_change_ok(inode, iattr);
	if (error)
		return error;

	error = inode_setattr(inode, iattr);
	if (error)
		return error;

	if (!sd_iattr) {
		/* setting attributes for the first time, allocate now */
		sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
		if (!sd_iattr)
			return -ENOMEM;
		/* assign default attributes */
		sd_iattr->ia_mode = sd->s_mode;
		sd_iattr->ia_uid = 0;
		sd_iattr->ia_gid = 0;
		sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
		sd->s_iattr = sd_iattr;
	}

	/* attributes were changed atleast once in past */

	if (ia_valid & ATTR_UID)
		sd_iattr->ia_uid = iattr->ia_uid;
	if (ia_valid & ATTR_GID)
		sd_iattr->ia_gid = iattr->ia_gid;
	if (ia_valid & ATTR_ATIME)
		sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
						inode->i_sb->s_time_gran);
	if (ia_valid & ATTR_MTIME)
		sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
						inode->i_sb->s_time_gran);
	if (ia_valid & ATTR_CTIME)
		sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
						inode->i_sb->s_time_gran);
	if (ia_valid & ATTR_MODE) {
		umode_t mode = iattr->ia_mode;

		if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
			mode &= ~S_ISGID;
		sd_iattr->ia_mode = sd->s_mode = mode;
	}

	return error;
}

static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
{
	inode->i_mode = mode;
	inode->i_uid = 0;
	inode->i_gid = 0;
	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
}

static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
{
	inode->i_mode = iattr->ia_mode;
	inode->i_uid = iattr->ia_uid;
	inode->i_gid = iattr->ia_gid;
	inode->i_atime = iattr->ia_atime;
	inode->i_mtime = iattr->ia_mtime;
	inode->i_ctime = iattr->ia_ctime;
}


/*
 * sysfs has a different i_mutex lock order behavior for i_mutex than other
 * filesystems; sysfs i_mutex is called in many places with subsystem locks
 * held. At the same time, many of the VFS locking rules do not apply to
 * sysfs at all (cross directory rename for example). To untangle this mess
 * (which gives false positives in lockdep), we're giving sysfs inodes their
 * own class for i_mutex.
 */
static struct lock_class_key sysfs_inode_imutex_key;

struct inode * sysfs_new_inode(mode_t mode, struct sysfs_dirent * sd)
{
	struct inode * inode = new_inode(sysfs_sb);
	if (inode) {
		inode->i_blocks = 0;
		inode->i_mapping->a_ops = &sysfs_aops;
		inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
		inode->i_op = &sysfs_inode_operations;
		lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);

		if (sd->s_iattr) {
			/* sysfs_dirent has non-default attributes
			 * get them for the new inode from persistent copy
			 * in sysfs_dirent
			 */
			set_inode_attr(inode, sd->s_iattr);
		} else
			set_default_inode_attr(inode, mode);
	}
	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) {
			struct sysfs_dirent * sd = dentry->d_fsdata;
			if ((inode = sysfs_new_inode(mode, sd))) {
				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;
}

/*
 * 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;

	BUG_ON(!sd || !sd->s_element);

	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;
}

static inline void orphan_all_buffers(struct inode *node)
{
	struct sysfs_buffer_collection *set;
	struct sysfs_buffer *buf;

	mutex_lock_nested(&node->i_mutex, I_MUTEX_CHILD);
	set = node->i_private;
	if (set) {
		list_for_each_entry(buf, &set->associates, associates) {
			down(&buf->sem);
			buf->orphaned = 1;
			up(&buf->sem);
		}
	}
	mutex_unlock(&node->i_mutex);
}


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

	if (dentry) {
		spin_lock(&dcache_lock);
		spin_lock(&dentry->d_lock);
		if (!(d_unhashed(dentry) && dentry->d_inode)) {
			inode = dentry->d_inode;
			spin_lock(&inode->i_lock);
			__iget(inode);
			spin_unlock(&inode->i_lock);
			dget_locked(dentry);
			__d_drop(dentry);
			spin_unlock(&dentry->d_lock);
			spin_unlock(&dcache_lock);
			simple_unlink(parent->d_inode, dentry);
			orphan_all_buffers(inode);
			iput(inode);
		} else {
			spin_unlock(&dentry->d_lock);
			spin_unlock(&dcache_lock);
		}
	}
}

int sysfs_hash_and_remove(struct dentry * dir, const char * name)
{
	struct sysfs_dirent * sd;
	struct sysfs_dirent * parent_sd;
	int found = 0;

	if (!dir)
		return -ENOENT;

	if (dir->d_inode == NULL)
		/* no inode means this hasn't been made visible yet */
		return -ENOENT;

	parent_sd = dir->d_fsdata;
	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
	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);
			found = 1;
			break;
		}
	}
	mutex_unlock(&dir->d_inode->i_mutex);

	return found ? 0 : -ENOENT;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* inode.c - basic inode and dentry operations.
	3	*
	4	* sysfs is Copyright (c) 2001-3 Patrick Mochel
	5	*
	6	* Please see Documentation/filesystems/sysfs.txt for more information.
	7	*/
	8
	9	#undef DEBUG
	10
	11	#include <linux/pagemap.h>
	12	#include <linux/namei.h>
	13	#include <linux/backing-dev.h>
16f7e0fe	14	#include <linux/capability.h>
995982ca	15	#include <linux/errno.h>
e8edc6e0	16	#include <linux/sched.h>
94bebf4d	17	#include <asm/semaphore.h>
1da177e4 LT	18	#include "sysfs.h"
	19
	20	extern struct super_block * sysfs_sb;
	21
f5e54d6e	22	static const struct address_space_operations sysfs_aops = {
1da177e4 LT	23	.readpage = simple_readpage,
	24	.prepare_write = simple_prepare_write,
	25	.commit_write = simple_commit_write
	26	};
	27
	28	static struct backing_dev_info sysfs_backing_dev_info = {
	29	.ra_pages = 0, /* No readahead */
	30	.capabilities = BDI_CAP_NO_ACCT_DIRTY \| BDI_CAP_NO_WRITEBACK,
	31	};
	32
c5ef1c42	33	static const struct inode_operations sysfs_inode_operations ={
988d186d MS	34	.setattr = sysfs_setattr,
	35	};
	36
b592fcfe EB	37	void sysfs_delete_inode(struct inode *inode)
	38	{
	39	/* Free the shadowed directory inode operations */
	40	if (sysfs_is_shadowed_inode(inode)) {
	41	kfree(inode->i_op);
	42	inode->i_op = NULL;
	43	}
	44	return generic_delete_inode(inode);
	45	}
	46
988d186d MS	47	int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
	48	{
	49	struct inode * inode = dentry->d_inode;
	50	struct sysfs_dirent * sd = dentry->d_fsdata;
	51	struct iattr * sd_iattr;
	52	unsigned int ia_valid = iattr->ia_valid;
	53	int error;
	54
	55	if (!sd)
	56	return -EINVAL;
	57
	58	sd_iattr = sd->s_iattr;
	59
	60	error = inode_change_ok(inode, iattr);
	61	if (error)
	62	return error;
	63
	64	error = inode_setattr(inode, iattr);
	65	if (error)
	66	return error;
	67
	68	if (!sd_iattr) {
	69	/* setting attributes for the first time, allocate now */
58d49283	70	sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
988d186d MS	71	if (!sd_iattr)
	72	return -ENOMEM;
	73	/* assign default attributes */
988d186d MS	74	sd_iattr->ia_mode = sd->s_mode;
	75	sd_iattr->ia_uid = 0;
	76	sd_iattr->ia_gid = 0;
	77	sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
	78	sd->s_iattr = sd_iattr;
	79	}
	80
	81	/* attributes were changed atleast once in past */
	82
	83	if (ia_valid & ATTR_UID)
	84	sd_iattr->ia_uid = iattr->ia_uid;
	85	if (ia_valid & ATTR_GID)
	86	sd_iattr->ia_gid = iattr->ia_gid;
	87	if (ia_valid & ATTR_ATIME)
	88	sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
	89	inode->i_sb->s_time_gran);
	90	if (ia_valid & ATTR_MTIME)
	91	sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
	92	inode->i_sb->s_time_gran);
	93	if (ia_valid & ATTR_CTIME)
	94	sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
	95	inode->i_sb->s_time_gran);
	96	if (ia_valid & ATTR_MODE) {
	97	umode_t mode = iattr->ia_mode;
	98
	99	if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
	100	mode &= ~S_ISGID;
9ca1eb32	101	sd_iattr->ia_mode = sd->s_mode = mode;
988d186d MS	102	}
	103
	104	return error;
	105	}
	106
8215534c MS	107	static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
	108	{
	109	inode->i_mode = mode;
	110	inode->i_uid = 0;
	111	inode->i_gid = 0;
	112	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	113	}
	114
	115	static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
	116	{
	117	inode->i_mode = iattr->ia_mode;
	118	inode->i_uid = iattr->ia_uid;
	119	inode->i_gid = iattr->ia_gid;
	120	inode->i_atime = iattr->ia_atime;
	121	inode->i_mtime = iattr->ia_mtime;
	122	inode->i_ctime = iattr->ia_ctime;
	123	}
	124
232ba9db AV	125
	126	/*
	127	* sysfs has a different i_mutex lock order behavior for i_mutex than other
	128	* filesystems; sysfs i_mutex is called in many places with subsystem locks
	129	* held. At the same time, many of the VFS locking rules do not apply to
	130	* sysfs at all (cross directory rename for example). To untangle this mess
	131	* (which gives false positives in lockdep), we're giving sysfs inodes their
	132	* own class for i_mutex.
	133	*/
	134	static struct lock_class_key sysfs_inode_imutex_key;
	135
8215534c	136	struct inode * sysfs_new_inode(mode_t mode, struct sysfs_dirent * sd)
1da177e4 LT	137	{
	138	struct inode * inode = new_inode(sysfs_sb);
	139	if (inode) {
1da177e4	140	inode->i_blocks = 0;
1da177e4 LT	141	inode->i_mapping->a_ops = &sysfs_aops;
1da177e4 LT	142	inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
8215534c	143	inode->i_op = &sysfs_inode_operations;
232ba9db	144	lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
8215534c MS	145
	146	if (sd->s_iattr) {
	147	/* sysfs_dirent has non-default attributes
	148	* get them for the new inode from persistent copy
	149	* in sysfs_dirent
	150	*/
	151	set_inode_attr(inode, sd->s_iattr);
	152	} else
	153	set_default_inode_attr(inode, mode);
1da177e4 LT	154	}
	155	return inode;
	156	}
	157
	158	int sysfs_create(struct dentry * dentry, int mode, int (init)(struct inode ))
	159	{
	160	int error = 0;
	161	struct inode * inode = NULL;
	162	if (dentry) {
	163	if (!dentry->d_inode) {
8215534c MS	164	struct sysfs_dirent * sd = dentry->d_fsdata;
8215534c MS	165	if ((inode = sysfs_new_inode(mode, sd))) {
1da177e4 LT	166	if (dentry->d_parent && dentry->d_parent->d_inode) {
	167	struct inode *p_inode = dentry->d_parent->d_inode;
	168	p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
	169	}
	170	goto Proceed;
	171	}
	172	else
	173	error = -ENOMEM;
	174	} else
	175	error = -EEXIST;
	176	} else
	177	error = -ENOENT;
	178	goto Done;
	179
	180	Proceed:
	181	if (init)
	182	error = init(inode);
	183	if (!error) {
	184	d_instantiate(dentry, inode);
	185	if (S_ISDIR(mode))
	186	dget(dentry); /* pin only directory dentry in core */
	187	} else
	188	iput(inode);
	189	Done:
	190	return error;
	191	}
	192
1da177e4 LT	193	/*
	194	* Get the name for corresponding element represented by the given sysfs_dirent
	195	*/
	196	const unsigned char * sysfs_get_name(struct sysfs_dirent *sd)
	197	{
	198	struct attribute * attr;
	199	struct bin_attribute * bin_attr;
	200	struct sysfs_symlink * sl;
	201
99cee0cd	202	BUG_ON(!sd \|\| !sd->s_element);
1da177e4 LT	203
	204	switch (sd->s_type) {
	205	case SYSFS_DIR:
	206	/* Always have a dentry so use that */
	207	return sd->s_dentry->d_name.name;
	208
	209	case SYSFS_KOBJ_ATTR:
	210	attr = sd->s_element;
	211	return attr->name;
	212
	213	case SYSFS_KOBJ_BIN_ATTR:
	214	bin_attr = sd->s_element;
	215	return bin_attr->attr.name;
	216
	217	case SYSFS_KOBJ_LINK:
	218	sl = sd->s_element;
	219	return sl->link_name;
	220	}
	221	return NULL;
	222	}
	223
94bebf4d ON	224	static inline void orphan_all_buffers(struct inode *node)
94bebf4d ON	225	{
e7b0d26a	226	struct sysfs_buffer_collection *set;
94bebf4d ON	227	struct sysfs_buffer *buf;
94bebf4d ON	228
d3fc373a	229	mutex_lock_nested(&node->i_mutex, I_MUTEX_CHILD);
e7b0d26a AS	230	set = node->i_private;
	231	if (set) {
	232	list_for_each_entry(buf, &set->associates, associates) {
	233	down(&buf->sem);
94bebf4d	234	buf->orphaned = 1;
e7b0d26a AS	235	up(&buf->sem);
e7b0d26a AS	236	}
94bebf4d ON	237	}
	238	mutex_unlock(&node->i_mutex);
	239	}
	240
1da177e4 LT	241
	242	/*
	243	* Unhashes the dentry corresponding to given sysfs_dirent
1b1dcc1b	244	* Called with parent inode's i_mutex held.
1da177e4 LT	245	*/
	246	void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent)
	247	{
	248	struct dentry * dentry = sd->s_dentry;
94bebf4d	249	struct inode *inode;
1da177e4 LT	250
	251	if (dentry) {
	252	spin_lock(&dcache_lock);
	253	spin_lock(&dentry->d_lock);
	254	if (!(d_unhashed(dentry) && dentry->d_inode)) {
94bebf4d ON	255	inode = dentry->d_inode;
	256	spin_lock(&inode->i_lock);
	257	__iget(inode);
	258	spin_unlock(&inode->i_lock);
1da177e4 LT	259	dget_locked(dentry);
	260	__d_drop(dentry);
	261	spin_unlock(&dentry->d_lock);
	262	spin_unlock(&dcache_lock);
	263	simple_unlink(parent->d_inode, dentry);
94bebf4d ON	264	orphan_all_buffers(inode);
94bebf4d ON	265	iput(inode);
1da177e4 LT	266	} else {
	267	spin_unlock(&dentry->d_lock);
	268	spin_unlock(&dcache_lock);
	269	}
	270	}
	271	}
	272
995982ca	273	int sysfs_hash_and_remove(struct dentry * dir, const char * name)
1da177e4 LT	274	{
1da177e4 LT	275	struct sysfs_dirent * sd;
641e6f30	276	struct sysfs_dirent * parent_sd;
995982ca	277	int found = 0;
641e6f30 GKH	278
641e6f30 GKH	279	if (!dir)
995982ca	280	return -ENOENT;
1da177e4	281
36676bcb JB	282	if (dir->d_inode == NULL)
36676bcb JB	283	/* no inode means this hasn't been made visible yet */
995982ca	284	return -ENOENT;
36676bcb	285
641e6f30	286	parent_sd = dir->d_fsdata;
d3fc373a	287	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
1da177e4 LT	288	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
	289	if (!sd->s_element)
	290	continue;
	291	if (!strcmp(sysfs_get_name(sd), name)) {
	292	list_del_init(&sd->s_sibling);
	293	sysfs_drop_dentry(sd, dir);
	294	sysfs_put(sd);
995982ca	295	found = 1;
1da177e4 LT	296	break;
	297	}
	298	}
1b1dcc1b	299	mutex_unlock(&dir->d_inode->i_mutex);
995982ca RD	300
995982ca RD	301	return found ? 0 : -ENOENT;
1da177e4	302	}