[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;

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;
		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, 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;
}

/*
 * 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 = NULL;

	/* 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);

	/* dget dentry if it's still alive */
	if (sd->s_dentry && sd->s_dentry->d_inode)
		dentry = dget_locked(sd->s_dentry);

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

	/* drop 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);
		}

		dput(dentry);
	}
}

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_type)
			continue;
		if (!strcmp(sd->s_name, name)) {
			list_del_init(&sd->s_sibling);
			sysfs_drop_dentry(sd, dir);
			found = 1;
			break;
		}
	}
	mutex_unlock(&dir->d_inode->i_mutex);

	if (!found)
		return -ENOENT;

	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
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;
dc351252	144	inode->i_ino = sd->s_ino;
232ba9db	145	lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
8215534c MS	146
	147	if (sd->s_iattr) {
	148	/* sysfs_dirent has non-default attributes
	149	* get them for the new inode from persistent copy
	150	* in sysfs_dirent
	151	*/
	152	set_inode_attr(inode, sd->s_iattr);
	153	} else
	154	set_default_inode_attr(inode, mode);
1da177e4 LT	155	}
	156	return inode;
	157	}
	158
	159	int sysfs_create(struct dentry * dentry, int mode, int (init)(struct inode ))
	160	{
	161	int error = 0;
	162	struct inode * inode = NULL;
	163	if (dentry) {
	164	if (!dentry->d_inode) {
8215534c MS	165	struct sysfs_dirent * sd = dentry->d_fsdata;
8215534c MS	166	if ((inode = sysfs_new_inode(mode, sd))) {
1da177e4 LT	167	if (dentry->d_parent && dentry->d_parent->d_inode) {
	168	struct inode *p_inode = dentry->d_parent->d_inode;
	169	p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
	170	}
	171	goto Proceed;
	172	}
	173	else
	174	error = -ENOMEM;
	175	} else
	176	error = -EEXIST;
	177	} else
	178	error = -ENOENT;
	179	goto Done;
	180
	181	Proceed:
	182	if (init)
	183	error = init(inode);
	184	if (!error) {
	185	d_instantiate(dentry, inode);
	186	if (S_ISDIR(mode))
	187	dget(dentry); /* pin only directory dentry in core */
	188	} else
	189	iput(inode);
	190	Done:
	191	return error;
	192	}
	193
1da177e4 LT	194	/*
1da177e4 LT	195	* Unhashes the dentry corresponding to given sysfs_dirent
1b1dcc1b	196	* Called with parent inode's i_mutex held.
1da177e4 LT	197	*/
	198	void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent)
	199	{
dd14cbc9	200	struct dentry *dentry = NULL;
1da177e4	201
dd14cbc9 TH	202	/* We're not holding a reference to ->s_dentry dentry but the
	203	* field will stay valid as long as sysfs_lock is held.
	204	*/
	205	spin_lock(&sysfs_lock);
	206	spin_lock(&dcache_lock);
	207
	208	/* dget dentry if it's still alive */
	209	if (sd->s_dentry && sd->s_dentry->d_inode)
	210	dentry = dget_locked(sd->s_dentry);
	211
	212	spin_unlock(&dcache_lock);
	213	spin_unlock(&sysfs_lock);
	214
	215	/* drop dentry */
1da177e4 LT	216	if (dentry) {
	217	spin_lock(&dcache_lock);
	218	spin_lock(&dentry->d_lock);
6aa054aa	219	if (!d_unhashed(dentry) && dentry->d_inode) {
1da177e4 LT	220	dget_locked(dentry);
	221	__d_drop(dentry);
	222	spin_unlock(&dentry->d_lock);
	223	spin_unlock(&dcache_lock);
	224	simple_unlink(parent->d_inode, dentry);
	225	} else {
	226	spin_unlock(&dentry->d_lock);
	227	spin_unlock(&dcache_lock);
	228	}
dd14cbc9 TH	229
dd14cbc9 TH	230	dput(dentry);
1da177e4 LT	231	}
	232	}
	233
995982ca	234	int sysfs_hash_and_remove(struct dentry * dir, const char * name)
1da177e4 LT	235	{
1da177e4 LT	236	struct sysfs_dirent * sd;
641e6f30	237	struct sysfs_dirent * parent_sd;
995982ca	238	int found = 0;
641e6f30 GKH	239
641e6f30 GKH	240	if (!dir)
995982ca	241	return -ENOENT;
1da177e4	242
36676bcb JB	243	if (dir->d_inode == NULL)
36676bcb JB	244	/* no inode means this hasn't been made visible yet */
995982ca	245	return -ENOENT;
36676bcb	246
641e6f30	247	parent_sd = dir->d_fsdata;
d3fc373a	248	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
1da177e4	249	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
3e519038	250	if (!sd->s_type)
1da177e4	251	continue;
0c096b50	252	if (!strcmp(sd->s_name, name)) {
1da177e4 LT	253	list_del_init(&sd->s_sibling);
1da177e4 LT	254	sysfs_drop_dentry(sd, dir);
995982ca	255	found = 1;
1da177e4 LT	256	break;
	257	}
	258	}
1b1dcc1b	259	mutex_unlock(&dir->d_inode->i_mutex);
995982ca	260
0ab66088 TH	261	if (!found)
	262	return -ENOENT;
	263
	264	sysfs_deactivate(sd);
	265	sysfs_put(sd);
	266	return 0;
1da177e4	267	}