dir.c

linux 内核源代码

	inode = ilookup(sysfs_sb, sd->s_ino);
	if (!inode)
		return;

	/* Drop any existing dentries associated with sd.
	 *
	 * For the dentry to be properly freed we need to grab a
	 * reference to the dentry under the dcache lock,  unhash it,
	 * and then put it.  The playing with the dentry count allows
	 * dput to immediately free the dentry  if it is not in use.
	 */
repeat:
	spin_lock(&dcache_lock);
	list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
		if (d_unhashed(dentry))
			continue;
		dget_locked(dentry);
		spin_lock(&dentry->d_lock);
		__d_drop(dentry);
		spin_unlock(&dentry->d_lock);
		spin_unlock(&dcache_lock);
		dput(dentry);
		goto repeat;
	}
	spin_unlock(&dcache_lock);

	/* adjust nlink and update timestamp */
	mutex_lock(&inode->i_mutex);

	inode->i_ctime = CURRENT_TIME;
	drop_nlink(inode);
	if (sysfs_type(sd) == SYSFS_DIR)
		drop_nlink(inode);

	mutex_unlock(&inode->i_mutex);

	iput(inode);
}

/**
 *	sysfs_addrm_finish - finish up sysfs_dirent add/remove
 *	@acxt: addrm context to finish up
 *
 *	Finish up sysfs_dirent add/remove.  Resources acquired by
 *	sysfs_addrm_start() are released and removed sysfs_dirents are
 *	cleaned up.  Timestamps on the parent inode are updated.
 *
 *	LOCKING:
 *	All mutexes acquired by sysfs_addrm_start() are released.
 */
void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
{
	/* release resources acquired by sysfs_addrm_start() */
	mutex_unlock(&sysfs_mutex);
	if (acxt->parent_inode) {
		struct inode *inode = acxt->parent_inode;

		/* if added/removed, update timestamps on the parent */
		if (acxt->cnt)
			inode->i_ctime = inode->i_mtime = CURRENT_TIME;

		mutex_unlock(&inode->i_mutex);
		iput(inode);
	}

	/* kill removed sysfs_dirents */
	while (acxt->removed) {
		struct sysfs_dirent *sd = acxt->removed;

		acxt->removed = sd->s_sibling;
		sd->s_sibling = NULL;

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

/**
 *	sysfs_find_dirent - find sysfs_dirent with the given name
 *	@parent_sd: sysfs_dirent to search under
 *	@name: name to look for
 *
 *	Look for sysfs_dirent with name @name under @parent_sd.
 *
 *	LOCKING:
 *	mutex_lock(sysfs_mutex)
 *
 *	RETURNS:
 *	Pointer to sysfs_dirent if found, NULL if not.
 */
struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
				       const unsigned char *name)
{
	struct sysfs_dirent *sd;

	for (sd = parent_sd->s_dir.children; sd; sd = sd->s_sibling)
		if (!strcmp(sd->s_name, name))
			return sd;
	return NULL;
}

/**
 *	sysfs_get_dirent - find and get sysfs_dirent with the given name
 *	@parent_sd: sysfs_dirent to search under
 *	@name: name to look for
 *
 *	Look for sysfs_dirent with name @name under @parent_sd and get
 *	it if found.
 *
 *	LOCKING:
 *	Kernel thread context (may sleep).  Grabs sysfs_mutex.
 *
 *	RETURNS:
 *	Pointer to sysfs_dirent if found, NULL if not.
 */
struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
				      const unsigned char *name)
{
	struct sysfs_dirent *sd;

	mutex_lock(&sysfs_mutex);
	sd = sysfs_find_dirent(parent_sd, name);
	sysfs_get(sd);
	mutex_unlock(&sysfs_mutex);

	return sd;
}

static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
		      const char *name, struct sysfs_dirent **p_sd)
{
	umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
	struct sysfs_addrm_cxt acxt;
	struct sysfs_dirent *sd;
	int rc;

	/* allocate */
	sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
	if (!sd)
		return -ENOMEM;
	sd->s_dir.kobj = kobj;

	/* link in */
	sysfs_addrm_start(&acxt, parent_sd);
	rc = sysfs_add_one(&acxt, sd);
	sysfs_addrm_finish(&acxt);

	if (rc == 0)
		*p_sd = sd;
	else
		sysfs_put(sd);

	return rc;
}

int sysfs_create_subdir(struct kobject *kobj, const char *name,
			struct sysfs_dirent **p_sd)
{
	return create_dir(kobj, kobj->sd, name, p_sd);
}

/**
 *	sysfs_create_dir - create a directory for an object.
 *	@kobj:		object we're creating directory for. 
 */
int sysfs_create_dir(struct kobject * kobj)
{
	struct sysfs_dirent *parent_sd, *sd;
	int error = 0;

	BUG_ON(!kobj);

	if (kobj->parent)
		parent_sd = kobj->parent->sd;
	else
		parent_sd = &sysfs_root;

	error = create_dir(kobj, parent_sd, kobject_name(kobj), &sd);
	if (!error)
		kobj->sd = sd;
	return error;
}

static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
				struct nameidata *nd)
{
	struct dentry *ret = NULL;
	struct sysfs_dirent *parent_sd = dentry->d_parent->d_fsdata;
	struct sysfs_dirent *sd;
	struct inode *inode;

	mutex_lock(&sysfs_mutex);

	sd = sysfs_find_dirent(parent_sd, dentry->d_name.name);

	/* no such entry */
	if (!sd) {
		ret = ERR_PTR(-ENOENT);
		goto out_unlock;
	}

	/* attach dentry and inode */
	inode = sysfs_get_inode(sd);
	if (!inode) {
		ret = ERR_PTR(-ENOMEM);
		goto out_unlock;
	}

	/* instantiate and hash dentry */
	dentry->d_op = &sysfs_dentry_ops;
	dentry->d_fsdata = sysfs_get(sd);
	d_instantiate(dentry, inode);
	d_rehash(dentry);

 out_unlock:
	mutex_unlock(&sysfs_mutex);
	return ret;
}

const struct inode_operations sysfs_dir_inode_operations = {
	.lookup		= sysfs_lookup,
	.setattr	= sysfs_setattr,
};

static void remove_dir(struct sysfs_dirent *sd)
{
	struct sysfs_addrm_cxt acxt;

	sysfs_addrm_start(&acxt, sd->s_parent);
	sysfs_remove_one(&acxt, sd);
	sysfs_addrm_finish(&acxt);
}

void sysfs_remove_subdir(struct sysfs_dirent *sd)
{
	remove_dir(sd);
}


static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
{
	struct sysfs_addrm_cxt acxt;
	struct sysfs_dirent **pos;

	if (!dir_sd)
		return;

	pr_debug("sysfs %s: removing dir\n", dir_sd->s_name);
	sysfs_addrm_start(&acxt, dir_sd);
	pos = &dir_sd->s_dir.children;
	while (*pos) {
		struct sysfs_dirent *sd = *pos;

		if (sysfs_type(sd) != SYSFS_DIR)
			sysfs_remove_one(&acxt, sd);
		else
			pos = &(*pos)->s_sibling;
	}
	sysfs_addrm_finish(&acxt);

	remove_dir(dir_sd);
}

/**
 *	sysfs_remove_dir - remove an object's directory.
 *	@kobj:	object.
 *
 *	The only thing special about this is that we remove any files in
 *	the directory before we remove the directory, and we've inlined
 *	what used to be sysfs_rmdir() below, instead of calling separately.
 */

void sysfs_remove_dir(struct kobject * kobj)
{
	struct sysfs_dirent *sd = kobj->sd;

	spin_lock(&sysfs_assoc_lock);
	kobj->sd = NULL;
	spin_unlock(&sysfs_assoc_lock);

	__sysfs_remove_dir(sd);
}

int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
{
	struct sysfs_dirent *sd = kobj->sd;
	struct dentry *parent = NULL;
	struct dentry *old_dentry = NULL, *new_dentry = NULL;
	const char *dup_name = NULL;
	int error;

	mutex_lock(&sysfs_rename_mutex);

	error = 0;
	if (strcmp(sd->s_name, new_name) == 0)
		goto out;	/* nothing to rename */

	/* get the original dentry */
	old_dentry = sysfs_get_dentry(sd);
	if (IS_ERR(old_dentry)) {
		error = PTR_ERR(old_dentry);
		old_dentry = NULL;
		goto out;
	}

	parent = old_dentry->d_parent;

	/* lock parent and get dentry for new name */
	mutex_lock(&parent->d_inode->i_mutex);
	mutex_lock(&sysfs_mutex);

	error = -EEXIST;
	if (sysfs_find_dirent(sd->s_parent, new_name))
		goto out_unlock;

	error = -ENOMEM;
	new_dentry = d_alloc_name(parent, new_name);
	if (!new_dentry)
		goto out_unlock;

	/* rename kobject and sysfs_dirent */
	error = -ENOMEM;
	new_name = dup_name = kstrdup(new_name, GFP_KERNEL);
	if (!new_name)
		goto out_unlock;

	error = kobject_set_name(kobj, "%s", new_name);
	if (error)
		goto out_unlock;

	dup_name = sd->s_name;
	sd->s_name = new_name;

	/* rename */
	d_add(new_dentry, NULL);
	d_move(old_dentry, new_dentry);

	error = 0;
 out_unlock:
	mutex_unlock(&sysfs_mutex);
	mutex_unlock(&parent->d_inode->i_mutex);
	kfree(dup_name);
	dput(old_dentry);
	dput(new_dentry);
 out:
	mutex_unlock(&sysfs_rename_mutex);
	return error;
}

int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
{
	struct sysfs_dirent *sd = kobj->sd;
	struct sysfs_dirent *new_parent_sd;
	struct dentry *old_parent, *new_parent = NULL;
	struct dentry *old_dentry = NULL, *new_dentry = NULL;
	int error;

	mutex_lock(&sysfs_rename_mutex);
	BUG_ON(!sd->s_parent);
	new_parent_sd = new_parent_kobj->sd ? new_parent_kobj->sd : &sysfs_root;

	error = 0;
	if (sd->s_parent == new_parent_sd)
		goto out;	/* nothing to move */

	/* get dentries */
	old_dentry = sysfs_get_dentry(sd);
	if (IS_ERR(old_dentry)) {
		error = PTR_ERR(old_dentry);
		old_dentry = NULL;
		goto out;
	}
	old_parent = old_dentry->d_parent;

	new_parent = sysfs_get_dentry(new_parent_sd);
	if (IS_ERR(new_parent)) {
		error = PTR_ERR(new_parent);
		new_parent = NULL;
		goto out;
	}

again:
	mutex_lock(&old_parent->d_inode->i_mutex);
	if (!mutex_trylock(&new_parent->d_inode->i_mutex)) {
		mutex_unlock(&old_parent->d_inode->i_mutex);
		goto again;
	}
	mutex_lock(&sysfs_mutex);

	error = -EEXIST;
	if (sysfs_find_dirent(new_parent_sd, sd->s_name))
		goto out_unlock;

	error = -ENOMEM;
	new_dentry = d_alloc_name(new_parent, sd->s_name);
	if (!new_dentry)
		goto out_unlock;

	error = 0;
	d_add(new_dentry, NULL);
	d_move(old_dentry, new_dentry);

	/* Remove from old parent's list and insert into new parent's list. */
	sysfs_unlink_sibling(sd);
	sysfs_get(new_parent_sd);
	sysfs_put(sd->s_parent);
	sd->s_parent = new_parent_sd;
	sysfs_link_sibling(sd);

 out_unlock:
	mutex_unlock(&sysfs_mutex);
	mutex_unlock(&new_parent->d_inode->i_mutex);
	mutex_unlock(&old_parent->d_inode->i_mutex);
 out:
	dput(new_parent);
	dput(old_dentry);
	dput(new_dentry);
	mutex_unlock(&sysfs_rename_mutex);
	return error;
}

/* Relationship between s_mode and the DT_xxx types */
static inline unsigned char dt_type(struct sysfs_dirent *sd)
{
	return (sd->s_mode >> 12) & 15;
}

static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
	struct dentry *dentry = filp->f_path.dentry;
	struct sysfs_dirent * parent_sd = dentry->d_fsdata;
	struct sysfs_dirent *pos;
	ino_t ino;

	if (filp->f_pos == 0) {
		ino = parent_sd->s_ino;
		if (filldir(dirent, ".", 1, filp->f_pos, ino, DT_DIR) == 0)
			filp->f_pos++;
	}
	if (filp->f_pos == 1) {
		if (parent_sd->s_parent)
			ino = parent_sd->s_parent->s_ino;
		else
			ino = parent_sd->s_ino;
		if (filldir(dirent, "..", 2, filp->f_pos, ino, DT_DIR) == 0)
			filp->f_pos++;
	}
	if ((filp->f_pos > 1) && (filp->f_pos < INT_MAX)) {
		mutex_lock(&sysfs_mutex);

		/* Skip the dentries we have already reported */
		pos = parent_sd->s_dir.children;
		while (pos && (filp->f_pos > pos->s_ino))
			pos = pos->s_sibling;

		for ( ; pos; pos = pos->s_sibling) {
			const char * name;
			int len;

			name = pos->s_name;
			len = strlen(name);
			filp->f_pos = ino = pos->s_ino;

			if (filldir(dirent, name, len, filp->f_pos, ino,
					 dt_type(pos)) < 0)
				break;
		}
		if (!pos)
			filp->f_pos = INT_MAX;
		mutex_unlock(&sysfs_mutex);
	}
	return 0;
}


const struct file_operations sysfs_dir_operations = {
	.read		= generic_read_dir,
	.readdir	= sysfs_readdir,
};