[mirror_ubuntu-focal-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;

void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *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;
	inode->i_ino = sd->s_ino;
	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, sd->s_mode);
}

/**
 *	sysfs_get_inode - get inode for sysfs_dirent
 *	@sd: sysfs_dirent to allocate inode for
 *
 *	Get inode for @sd.  If such inode doesn't exist, a new inode
 *	is allocated and basics are initialized.  New inode is
 *	returned locked.
 *
 *	LOCKING:
 *	Kernel thread context (may sleep).
 *
 *	RETURNS:
 *	Pointer to allocated inode on success, NULL on failure.
 */
struct inode * sysfs_get_inode(struct sysfs_dirent *sd)
{
	struct inode *inode;

	inode = iget_locked(sysfs_sb, sd->s_ino);
	if (inode && (inode->i_state & I_NEW))
		sysfs_init_inode(sd, inode);

	return inode;
}

/**
 *	sysfs_instantiate - instantiate dentry
 *	@dentry: dentry to be instantiated
 *	@inode: inode associated with @sd
 *
 *	Unlock @inode if locked and instantiate @dentry with @inode.
 *
 *	LOCKING:
 *	None.
 */
void sysfs_instantiate(struct dentry *dentry, struct inode *inode)
{
	BUG_ON(!dentry || dentry->d_inode);

	if (inode->i_state & I_NEW) {
		unlock_new_inode(inode);

		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;
		}
	}

	d_instantiate(dentry, inode);
}

/**
 *	sysfs_drop_dentry - drop dentry for the specified sysfs_dirent
 *	@sd: target sysfs_dirent
 *
 *	Drop dentry for @sd.  @sd must have been unlinked from its
 *	parent on entry to this function such that it can't be looked
 *	up anymore.
 *
 *	@sd->s_dentry which is protected with sysfs_lock points to the
 *	currently associated dentry but we're not holding a reference
 *	to it and racing with dput().  Grab dcache_lock and verify
 *	dentry before dropping it.  If @sd->s_dentry is NULL or dput()
 *	beats us, no need to bother.
 */
void sysfs_drop_dentry(struct sysfs_dirent *sd)
{
	struct dentry *dentry = NULL, *parent = NULL;
	struct inode *dir;
	struct timespec curtime;

	/* We're not holding a reference to ->s_dentry dentry but the
	 * field will stay valid as long as sysfs_lock is held.
	 */
	spin_lock(&sysfs_lock);
	spin_lock(&dcache_lock);

	if (sd->s_dentry && sd->s_dentry->d_inode) {
		/* get dentry if it's there and dput() didn't kill it yet */
		dentry = dget_locked(sd->s_dentry);
		parent = dentry->d_parent;
	} else if (sd->s_parent->s_dentry->d_inode) {
		/* We need to update the parent even if dentry for the
		 * victim itself doesn't exist.
		 */
		parent = dget_locked(sd->s_parent->s_dentry);
	}

	/* drop */
	if (dentry) {
		spin_lock(&dentry->d_lock);
		__d_drop(dentry);
		spin_unlock(&dentry->d_lock);
	}

	spin_unlock(&dcache_lock);
	spin_unlock(&sysfs_lock);

	/* nothing to do if the parent isn't in dcache */
	if (!parent)
		return;

	/* adjust nlink and update timestamp */
	dir = parent->d_inode;
	mutex_lock(&dir->i_mutex);

	curtime = CURRENT_TIME;

	dir->i_ctime = dir->i_mtime = curtime;

	if (dentry) {
		dentry->d_inode->i_ctime = curtime;
		drop_nlink(dentry->d_inode);
		if (sd->s_type & SYSFS_DIR) {
			drop_nlink(dentry->d_inode);
			drop_nlink(dir);
			/* XXX: unpin if directory, this will go away soon */
			dput(dentry);
		}
	}

	mutex_unlock(&dir->i_mutex);

	/* bye bye */
	if (dentry)
		dput(dentry);
	else
		dput(parent);
}

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

	if (!dir)
		return -ENOENT;

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

	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
	for (pos = &parent_sd->s_children; *pos; pos = &(*pos)->s_sibling) {
		sd = *pos;

		if (!sd->s_type)
			continue;
		if (!strcmp(sd->s_name, name)) {
			*pos = sd->s_sibling;
			sd->s_sibling = NULL;
			found = 1;
			break;
		}
	}
	mutex_unlock(&dir->d_inode->i_mutex);

	if (!found)
		return -ENOENT;

	sysfs_drop_dentry(sd);
	sysfs_deactivate(sd);
	sysfs_put(sd);

	return 0;
}
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
fc9f54b9	136	void sysfs_init_inode(struct sysfs_dirent sd, struct inode inode)
1da177e4	137	{
fc9f54b9 TH	138	inode->i_blocks = 0;
	139	inode->i_mapping->a_ops = &sysfs_aops;
	140	inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
	141	inode->i_op = &sysfs_inode_operations;
	142	inode->i_ino = sd->s_ino;
	143	lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
	144
	145	if (sd->s_iattr) {
	146	/* sysfs_dirent has non-default attributes
	147	* get them for the new inode from persistent copy
	148	* in sysfs_dirent
	149	*/
	150	set_inode_attr(inode, sd->s_iattr);
	151	} else
	152	set_default_inode_attr(inode, sd->s_mode);
	153	}
	154
	155	/**
8312a8d7	156	* sysfs_get_inode - get inode for sysfs_dirent
fc9f54b9 TH	157	* @sd: sysfs_dirent to allocate inode for
fc9f54b9 TH	158	*
8312a8d7 TH	159	* Get inode for @sd. If such inode doesn't exist, a new inode
	160	* is allocated and basics are initialized. New inode is
	161	* returned locked.
fc9f54b9 TH	162	*
	163	* LOCKING:
	164	* Kernel thread context (may sleep).
	165	*
	166	* RETURNS:
	167	* Pointer to allocated inode on success, NULL on failure.
	168	*/
8312a8d7	169	struct inode * sysfs_get_inode(struct sysfs_dirent *sd)
fc9f54b9 TH	170	{
	171	struct inode *inode;
	172
8312a8d7 TH	173	inode = iget_locked(sysfs_sb, sd->s_ino);
8312a8d7 TH	174	if (inode && (inode->i_state & I_NEW))
fc9f54b9 TH	175	sysfs_init_inode(sd, inode);
fc9f54b9 TH	176
1da177e4 LT	177	return inode;
	178	}
	179
fc9f54b9 TH	180	/**
	181	* sysfs_instantiate - instantiate dentry
	182	* @dentry: dentry to be instantiated
	183	* @inode: inode associated with @sd
	184	*
8312a8d7	185	* Unlock @inode if locked and instantiate @dentry with @inode.
fc9f54b9 TH	186	*
	187	* LOCKING:
	188	* None.
	189	*/
	190	void sysfs_instantiate(struct dentry dentry, struct inode inode)
1da177e4	191	{
fc9f54b9 TH	192	BUG_ON(!dentry \|\| dentry->d_inode);
fc9f54b9 TH	193
8312a8d7 TH	194	if (inode->i_state & I_NEW) {
	195	unlock_new_inode(inode);
	196
	197	if (dentry->d_parent && dentry->d_parent->d_inode) {
	198	struct inode *p_inode = dentry->d_parent->d_inode;
	199	p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
	200	}
fc9f54b9 TH	201	}
	202
	203	d_instantiate(dentry, inode);
1da177e4 LT	204	}
1da177e4 LT	205
dbde0fcf TH	206	/**
	207	* sysfs_drop_dentry - drop dentry for the specified sysfs_dirent
	208	* @sd: target sysfs_dirent
	209	*
	210	* Drop dentry for @sd. @sd must have been unlinked from its
	211	* parent on entry to this function such that it can't be looked
	212	* up anymore.
	213	*
	214	* @sd->s_dentry which is protected with sysfs_lock points to the
	215	* currently associated dentry but we're not holding a reference
	216	* to it and racing with dput(). Grab dcache_lock and verify
	217	* dentry before dropping it. If @sd->s_dentry is NULL or dput()
	218	* beats us, no need to bother.
1da177e4	219	*/
dbde0fcf	220	void sysfs_drop_dentry(struct sysfs_dirent *sd)
1da177e4	221	{
dbde0fcf TH	222	struct dentry dentry = NULL, parent = NULL;
	223	struct inode *dir;
	224	struct timespec curtime;
1da177e4	225
dd14cbc9 TH	226	/* We're not holding a reference to ->s_dentry dentry but the
	227	* field will stay valid as long as sysfs_lock is held.
	228	*/
	229	spin_lock(&sysfs_lock);
	230	spin_lock(&dcache_lock);
	231
dbde0fcf TH	232	if (sd->s_dentry && sd->s_dentry->d_inode) {
dbde0fcf TH	233	/* get dentry if it's there and dput() didn't kill it yet */
dd14cbc9	234	dentry = dget_locked(sd->s_dentry);
dbde0fcf TH	235	parent = dentry->d_parent;
	236	} else if (sd->s_parent->s_dentry->d_inode) {
	237	/* We need to update the parent even if dentry for the
	238	* victim itself doesn't exist.
	239	*/
	240	parent = dget_locked(sd->s_parent->s_dentry);
	241	}
	242
	243	/* drop */
	244	if (dentry) {
	245	spin_lock(&dentry->d_lock);
	246	__d_drop(dentry);
	247	spin_unlock(&dentry->d_lock);
	248	}
dd14cbc9 TH	249
	250	spin_unlock(&dcache_lock);
	251	spin_unlock(&sysfs_lock);
	252
dbde0fcf TH	253	/* nothing to do if the parent isn't in dcache */
	254	if (!parent)
	255	return;
	256
	257	/* adjust nlink and update timestamp */
	258	dir = parent->d_inode;
	259	mutex_lock(&dir->i_mutex);
	260
	261	curtime = CURRENT_TIME;
	262
	263	dir->i_ctime = dir->i_mtime = curtime;
	264
1da177e4	265	if (dentry) {
dbde0fcf TH	266	dentry->d_inode->i_ctime = curtime;
	267	drop_nlink(dentry->d_inode);
	268	if (sd->s_type & SYSFS_DIR) {
	269	drop_nlink(dentry->d_inode);
	270	drop_nlink(dir);
	271	/* XXX: unpin if directory, this will go away soon */
	272	dput(dentry);
1da177e4	273	}
dbde0fcf TH	274	}
	275
	276	mutex_unlock(&dir->i_mutex);
dd14cbc9	277
dbde0fcf TH	278	/* bye bye */
dbde0fcf TH	279	if (dentry)
dd14cbc9	280	dput(dentry);
dbde0fcf TH	281	else
dbde0fcf TH	282	dput(parent);
1da177e4 LT	283	}
1da177e4 LT	284
995982ca	285	int sysfs_hash_and_remove(struct dentry * dir, const char * name)
1da177e4	286	{
0c73f18b TH	287	struct sysfs_dirent *pos, sd;
0c73f18b TH	288	struct sysfs_dirent *parent_sd = dir->d_fsdata;
995982ca	289	int found = 0;
641e6f30 GKH	290
641e6f30 GKH	291	if (!dir)
995982ca	292	return -ENOENT;
1da177e4	293
36676bcb JB	294	if (dir->d_inode == NULL)
36676bcb JB	295	/* no inode means this hasn't been made visible yet */
995982ca	296	return -ENOENT;
36676bcb	297
d3fc373a	298	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
0c73f18b TH	299	for (pos = &parent_sd->s_children; pos; pos = &(pos)->s_sibling) {
	300	sd = *pos;
	301
3e519038	302	if (!sd->s_type)
1da177e4	303	continue;
0c096b50	304	if (!strcmp(sd->s_name, name)) {
0c73f18b TH	305	*pos = sd->s_sibling;
0c73f18b TH	306	sd->s_sibling = NULL;
995982ca	307	found = 1;
1da177e4 LT	308	break;
	309	}
	310	}
1b1dcc1b	311	mutex_unlock(&dir->d_inode->i_mutex);
995982ca	312
0ab66088 TH	313	if (!found)
	314	return -ENOENT;
	315
dbde0fcf	316	sysfs_drop_dentry(sd);
0ab66088 TH	317	sysfs_deactivate(sd);
0ab66088 TH	318	sysfs_put(sd);
dbde0fcf	319
0ab66088	320	return 0;
1da177e4	321	}