Commit ff4dd081 authored by Al Viro's avatar Al Viro Committed by Christoph Hellwig
Browse files

configfs: stash the data we need into configfs_buffer at open time 



simplifies the ->read()/->write()/->release() instances nicely

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 089cf7f6

fs/configfs/file.c

+95 −134
Original line number Diff line number Diff line
@@ -39,24 +39,18 @@ struct configfs_buffer { 
	bool			write_in_progress;

	char			*bin_buffer;

	int			bin_buffer_size;

	int			cb_max_size;

	struct config_item	*item;

	struct module		*owner;

	union {

		struct configfs_attribute	*attr;

		struct configfs_bin_attribute	*bin_attr;

	};

};





/**

 *	fill_read_buffer - allocate and fill buffer from item.

 *	@dentry:	dentry pointer.

 *	@buffer:	data buffer for file.

 *

 *	Allocate @buffer->page, if it hasn't been already, then call the

 *	config_item's show() method to fill the buffer with this attribute's

 *	data.

 *	This is called only once, on the file's first read.

 */

static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buffer)

static int fill_read_buffer(struct configfs_buffer * buffer)

{

	struct configfs_attribute * attr = to_attr(dentry);

	struct config_item * item = to_item(dentry->d_parent);

	int ret = 0;

	ssize_t count;



	if (!buffer->page)
@@ -64,15 +58,15 @@ static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buf 
	if (!buffer->page)

		return -ENOMEM;



	count = attr->show(item, buffer->page);

	count = buffer->attr->show(buffer->item, buffer->page);

	if (count < 0)

		return count;

	if (WARN_ON_ONCE(count > (ssize_t)SIMPLE_ATTR_SIZE))

		return -EIO;



	BUG_ON(count > (ssize_t)SIMPLE_ATTR_SIZE);

	if (count >= 0) {

	buffer->needs_read_fill = 0;

	buffer->count = count;

	} else

		ret = count;

	return ret;

	return 0;

}



/**
@@ -102,7 +96,8 @@ configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *pp 


	mutex_lock(&buffer->mutex);

	if (buffer->needs_read_fill) {

		if ((retval = fill_read_buffer(file->f_path.dentry,buffer)))

		retval = fill_read_buffer(buffer);

		if (retval)

			goto out;

	}

	pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
@@ -139,9 +134,6 @@ configfs_read_bin_file(struct file *file, char __user *buf, 
		       size_t count, loff_t *ppos)

{

	struct configfs_buffer *buffer = file->private_data;

	struct dentry *dentry = file->f_path.dentry;

	struct config_item *item = to_item(dentry->d_parent);

	struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);

	ssize_t retval = 0;

	ssize_t len = min_t(size_t, count, PAGE_SIZE);
@@ -156,14 +148,14 @@ configfs_read_bin_file(struct file *file, char __user *buf, 


	if (buffer->needs_read_fill) {

		/* perform first read with buf == NULL to get extent */

		len = bin_attr->read(item, NULL, 0);

		len = buffer->bin_attr->read(buffer->item, NULL, 0);

		if (len <= 0) {

			retval = len;

			goto out;

		}



		/* do not exceed the maximum value */

		if (bin_attr->cb_max_size && len > bin_attr->cb_max_size) {

		if (buffer->cb_max_size && len > buffer->cb_max_size) {

			retval = -EFBIG;

			goto out;

		}
@@ -176,7 +168,8 @@ configfs_read_bin_file(struct file *file, char __user *buf, 
		buffer->bin_buffer_size = len;



		/* perform second read to fill buffer */

		len = bin_attr->read(item, buffer->bin_buffer, len);

		len = buffer->bin_attr->read(buffer->item,

					     buffer->bin_buffer, len);

		if (len < 0) {

			retval = len;

			vfree(buffer->bin_buffer);
@@ -226,25 +219,10 @@ fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size 
	return error ? -EFAULT : count;

}





/**

 *	flush_write_buffer - push buffer to config_item.

 *	@dentry:	dentry to the attribute

 *	@buffer:	data buffer for file.

 *	@count:		number of bytes

 *

 *	Get the correct pointers for the config_item and the attribute we're

 *	dealing with, then call the store() method for the attribute,

 *	passing the buffer that we acquired in fill_write_buffer().

 */



static int

flush_write_buffer(struct dentry * dentry, struct configfs_buffer * buffer, size_t count)

flush_write_buffer(struct configfs_buffer *buffer, size_t count)

{

	struct configfs_attribute * attr = to_attr(dentry);

	struct config_item * item = to_item(dentry->d_parent);



	return attr->store(item, buffer->page, count);

	return buffer->attr->store(buffer->item, buffer->page, count);

}
@@ -274,7 +252,7 @@ configfs_write_file(struct file *file, const char __user *buf, size_t count, lof 
	mutex_lock(&buffer->mutex);

	len = fill_write_buffer(buffer, buf, count);

	if (len > 0)

		len = flush_write_buffer(file->f_path.dentry, buffer, len);

		len = flush_write_buffer(buffer, len);

	if (len > 0)

		*ppos += len;

	mutex_unlock(&buffer->mutex);
@@ -299,8 +277,6 @@ configfs_write_bin_file(struct file *file, const char __user *buf, 
			size_t count, loff_t *ppos)

{

	struct configfs_buffer *buffer = file->private_data;

	struct dentry *dentry = file->f_path.dentry;

	struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);

	void *tbuf = NULL;

	ssize_t len;
@@ -316,8 +292,8 @@ configfs_write_bin_file(struct file *file, const char __user *buf, 
	/* buffer grows? */

	if (*ppos + count > buffer->bin_buffer_size) {



		if (bin_attr->cb_max_size &&

			*ppos + count > bin_attr->cb_max_size) {

		if (buffer->cb_max_size &&

			*ppos + count > buffer->cb_max_size) {

			len = -EFBIG;

			goto out;

		}
@@ -349,31 +325,45 @@ configfs_write_bin_file(struct file *file, const char __user *buf, 
	return len;

}



static int check_perm(struct inode * inode, struct file * file, int type)

static int __configfs_open_file(struct inode *inode, struct file *file, int type)

{

	struct config_item *item = configfs_get_config_item(file->f_path.dentry->d_parent);

	struct configfs_attribute * attr = to_attr(file->f_path.dentry);

	struct configfs_bin_attribute *bin_attr = NULL;

	struct dentry *dentry = file->f_path.dentry;

	struct configfs_attribute *attr;

	struct configfs_buffer *buffer;

	struct configfs_item_operations * ops = NULL;

	int error = 0;

	int error;



	error = -ENOMEM;

	buffer = kzalloc(sizeof(struct configfs_buffer), GFP_KERNEL);

	if (!buffer)

		goto out;



	error = -EINVAL;

	buffer->item = configfs_get_config_item(dentry->d_parent);

	if (!buffer->item)

		goto out_free_buffer;



	if (!item || !attr)

		goto Einval;

	attr = to_attr(dentry);

	if (!attr)

		goto out_put_item;



	if (type & CONFIGFS_ITEM_BIN_ATTR)

		bin_attr = to_bin_attr(file->f_path.dentry);

	if (type & CONFIGFS_ITEM_BIN_ATTR) {

		buffer->bin_attr = to_bin_attr(dentry);

		buffer->cb_max_size = buffer->bin_attr->cb_max_size;

	} else {

		buffer->attr = attr;

	}



	buffer->owner = attr->ca_owner;

	/* Grab the module reference for this attribute if we have one */

	if (!try_module_get(attr->ca_owner)) {

	error = -ENODEV;

		goto Done;

	}

	if (!try_module_get(buffer->owner))

		goto out_put_item;



	if (item->ci_type)

		ops = item->ci_type->ct_item_ops;

	else

		goto Eaccess;

	error = -EACCES;

	if (!buffer->item->ci_type)

		goto out_put_module;



	buffer->ops = buffer->item->ci_type->ct_item_ops;



	/* File needs write support.

	 * The inode's perms must say it's ok,
@@ -381,13 +371,11 @@ static int check_perm(struct inode * inode, struct file * file, int type) 
	 */

	if (file->f_mode & FMODE_WRITE) {

		if (!(inode->i_mode & S_IWUGO))

			goto Eaccess;



			goto out_put_module;

		if ((type & CONFIGFS_ITEM_ATTR) && !attr->store)

			goto Eaccess;



		if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->write)

			goto Eaccess;

			goto out_put_module;

		if ((type & CONFIGFS_ITEM_BIN_ATTR) && !buffer->bin_attr->write)

			goto out_put_module;

	}



	/* File needs read support.
@@ -396,90 +384,65 @@ static int check_perm(struct inode * inode, struct file * file, int type) 
	 */

	if (file->f_mode & FMODE_READ) {

		if (!(inode->i_mode & S_IRUGO))

			goto Eaccess;



			goto out_put_module;

		if ((type & CONFIGFS_ITEM_ATTR) && !attr->show)

			goto Eaccess;



		if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->read)

			goto Eaccess;

			goto out_put_module;

		if ((type & CONFIGFS_ITEM_BIN_ATTR) && !buffer->bin_attr->read)

			goto out_put_module;

	}



	/* No error? Great, allocate a buffer for the file, and store it

	 * it in file->private_data for easy access.

	 */

	buffer = kzalloc(sizeof(struct configfs_buffer),GFP_KERNEL);

	if (!buffer) {

		error = -ENOMEM;

		goto Enomem;

	}

	mutex_init(&buffer->mutex);

	buffer->needs_read_fill = 1;

	buffer->read_in_progress = false;

	buffer->write_in_progress = false;

	buffer->ops = ops;

	file->private_data = buffer;

	goto Done;

	return 0;



 Einval:

	error = -EINVAL;

	goto Done;

 Eaccess:

	error = -EACCES;

 Enomem:

	module_put(attr->ca_owner);

 Done:

	if (error && item)

		config_item_put(item);

out_put_module:

	module_put(buffer->owner);

out_put_item:

	config_item_put(buffer->item);

out_free_buffer:

	kfree(buffer);

out:

	return error;

}



static int configfs_release(struct inode *inode, struct file *filp)

{

	struct config_item * item = to_item(filp->f_path.dentry->d_parent);

	struct configfs_attribute * attr = to_attr(filp->f_path.dentry);

	struct module * owner = attr->ca_owner;

	struct configfs_buffer *buffer = filp->private_data;



	if (item)

		config_item_put(item);

	/* After this point, attr should not be accessed. */

	module_put(owner);



	if (buffer) {

	if (buffer->item)

		config_item_put(buffer->item);

	module_put(buffer->owner);

	if (buffer->page)

		free_page((unsigned long)buffer->page);

	mutex_destroy(&buffer->mutex);

	kfree(buffer);

	}

	return 0;

}



static int configfs_open_file(struct inode *inode, struct file *filp)

{

	return check_perm(inode, filp, CONFIGFS_ITEM_ATTR);

	return __configfs_open_file(inode, filp, CONFIGFS_ITEM_ATTR);

}



static int configfs_open_bin_file(struct inode *inode, struct file *filp)

{

	return check_perm(inode, filp, CONFIGFS_ITEM_BIN_ATTR);

	return __configfs_open_file(inode, filp, CONFIGFS_ITEM_BIN_ATTR);

}



static int configfs_release_bin_file(struct inode *inode, struct file *filp)

static int configfs_release_bin_file(struct inode *inode, struct file *file)

{

	struct configfs_buffer *buffer = filp->private_data;

	struct dentry *dentry = filp->f_path.dentry;

	struct config_item *item = to_item(dentry->d_parent);

	struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);

	ssize_t len = 0;

	int ret;

	struct configfs_buffer *buffer = file->private_data;



	buffer->read_in_progress = false;



	if (buffer->write_in_progress) {

		buffer->write_in_progress = false;



		len = bin_attr->write(item, buffer->bin_buffer,

		/* result of ->release() is ignored */

		buffer->bin_attr->write(buffer->item, buffer->bin_buffer,

				buffer->bin_buffer_size);



		/* vfree on NULL is safe */
@@ -489,10 +452,8 @@ static int configfs_release_bin_file(struct inode *inode, struct file *filp) 
		buffer->needs_read_fill = 1;

	}



	ret = configfs_release(inode, filp);

	if (len < 0)

		return len;

	return ret;

	configfs_release(inode, file);

	return 0;

}