fs/sysfs/inode.c - kernel/msm-4.19 - Gitiles

 /*
  * 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 "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 struct inode_operations sysfs_inode_operations ={
 	.setattr	= sysfs_setattr,
 };

 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_blksize = PAGE_CACHE_SIZE;
 		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;
 }


 /*
  * 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;

 	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;

 	if (!dir)
 		return;

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

 	parent_sd = dir->d_fsdata;
 	mutex_lock(&dir->d_inode->i_mutex);
 	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;
 		}
 	}
 	mutex_unlock(&dir->d_inode->i_mutex);
 }
	/*
	* 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 "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 struct inode_operations sysfs_inode_operations ={
	.setattr = sysfs_setattr,
	};

	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_blksize = PAGE_CACHE_SIZE;
	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;
	}


	/*
	* 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;

	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;

	if (!dir)
	return;

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

	parent_sd = dir->d_fsdata;
	mutex_lock(&dir->d_inode->i_mutex);
	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;
	}
	}
	mutex_unlock(&dir->d_inode->i_mutex);
	}