Commit 7fe1e79b authored by Bart Van Assche's avatar Bart Van Assche Committed by Christoph Hellwig
Browse files

configfs: implement the .read_iter and .write_iter methods 



Configfs is one of the few filesystems that does not yet support the
.read_iter and .write_iter callbacks. This patch adds support for these
methods in configfs.

Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
[hch: split out a separate fix]
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 44b9a000

fs/configfs/file.c

+42 −42
Original line number Diff line number Diff line
@@ -14,7 +14,7 @@ 
#include <linux/mutex.h>

#include <linux/vmalloc.h>

#include <linux/uaccess.h>



#include <linux/uio.h>

#include <linux/configfs.h>

#include "configfs_internal.h"
@@ -77,9 +77,9 @@ static int fill_read_buffer(struct file *file, struct configfs_buffer *buffer) 
	return 0;

}



static ssize_t

configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)

static ssize_t configfs_read_iter(struct kiocb *iocb, struct iov_iter *to)

{

	struct file *file = iocb->ki_filp;

	struct configfs_buffer *buffer = file->private_data;

	ssize_t retval = 0;
@@ -89,23 +89,24 @@ configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *pp 
		if (retval)

			goto out;

	}

	pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",

		 __func__, count, *ppos, buffer->page);

	retval = simple_read_from_buffer(buf, count, ppos, buffer->page,

					 buffer->count);

	pr_debug("%s: count = %zd, pos = %lld, buf = %s\n",

		 __func__, iov_iter_count(to), iocb->ki_pos, buffer->page);

	retval = copy_to_iter(buffer->page, buffer->count, to);

	iocb->ki_pos += retval;

	if (retval == 0)

		retval = -EFAULT;

out:

	mutex_unlock(&buffer->mutex);

	return retval;

}



static ssize_t

configfs_read_bin_file(struct file *file, char __user *buf,

		       size_t count, loff_t *ppos)

static ssize_t configfs_bin_read_iter(struct kiocb *iocb, struct iov_iter *to)

{

	struct file *file = iocb->ki_filp;

	struct configfs_fragment *frag = to_frag(file);

	struct configfs_buffer *buffer = file->private_data;

	ssize_t retval = 0;

	ssize_t len = min_t(size_t, count, PAGE_SIZE);

	ssize_t len;



	mutex_lock(&buffer->mutex);
@@ -161,31 +162,31 @@ configfs_read_bin_file(struct file *file, char __user *buf, 
		buffer->needs_read_fill = 0;

	}



	retval = simple_read_from_buffer(buf, count, ppos, buffer->bin_buffer,

					buffer->bin_buffer_size);

	retval = copy_to_iter(buffer->bin_buffer, buffer->bin_buffer_size, to);

	iocb->ki_pos += retval;

	if (retval == 0)

		retval = -EFAULT;

out:

	mutex_unlock(&buffer->mutex);

	return retval;

}



static int

fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size_t count)

static int fill_write_buffer(struct configfs_buffer *buffer,

			     struct iov_iter *from)

{

	int error;

	int copied;



	if (!buffer->page)

		buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);

	if (!buffer->page)

		return -ENOMEM;



	if (count >= SIMPLE_ATTR_SIZE)

		count = SIMPLE_ATTR_SIZE - 1;

	error = copy_from_user(buffer->page,buf,count);

	copied = copy_from_iter(buffer->page, SIMPLE_ATTR_SIZE - 1, from);

	buffer->needs_read_fill = 1;

	/* if buf is assumed to contain a string, terminate it by \0,

	 * so e.g. sscanf() can scan the string easily */

	buffer->page[count] = 0;

	return error ? -EFAULT : count;

	buffer->page[copied] = 0;

	return copied ? : -EFAULT;

}



static int
@@ -209,28 +210,29 @@ flush_write_buffer(struct file *file, struct configfs_buffer *buffer, size_t cou 
 * Hint: if you're writing a value, first read the file, modify only the value

 * you're changing, then write entire buffer back.

 */

static ssize_t

configfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)

static ssize_t configfs_write_iter(struct kiocb *iocb, struct iov_iter *from)

{

	struct file *file = iocb->ki_filp;

	struct configfs_buffer *buffer = file->private_data;

	ssize_t len;



	mutex_lock(&buffer->mutex);

	len = fill_write_buffer(buffer, buf, count);

	len = fill_write_buffer(buffer, from);

	if (len > 0)

		len = flush_write_buffer(file, buffer, len);

	if (len > 0)

		*ppos += len;

		iocb->ki_pos += len;

	mutex_unlock(&buffer->mutex);

	return len;

}



static ssize_t

configfs_write_bin_file(struct file *file, const char __user *buf,

			size_t count, loff_t *ppos)

static ssize_t configfs_bin_write_iter(struct kiocb *iocb,

				       struct iov_iter *from)

{

	struct file *file = iocb->ki_filp;

	struct configfs_buffer *buffer = file->private_data;

	void *tbuf = NULL;

	size_t end_offset;

	ssize_t len;



	mutex_lock(&buffer->mutex);
@@ -243,15 +245,14 @@ configfs_write_bin_file(struct file *file, const char __user *buf, 
	buffer->write_in_progress = true;



	/* buffer grows? */

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



		if (buffer->cb_max_size &&

			*ppos + count > buffer->cb_max_size) {

	end_offset = iocb->ki_pos + iov_iter_count(from);

	if (end_offset > buffer->bin_buffer_size) {

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

			len = -EFBIG;

			goto out;

		}



		tbuf = vmalloc(*ppos + count);

		tbuf = vmalloc(end_offset);

		if (tbuf == NULL) {

			len = -ENOMEM;

			goto out;
@@ -266,16 +267,15 @@ configfs_write_bin_file(struct file *file, const char __user *buf, 


		/* clear the new area */

		memset(tbuf + buffer->bin_buffer_size, 0,

			*ppos + count - buffer->bin_buffer_size);

			end_offset - buffer->bin_buffer_size);

		buffer->bin_buffer = tbuf;

		buffer->bin_buffer_size = *ppos + count;

		buffer->bin_buffer_size = end_offset;

	}



	len = simple_write_to_buffer(buffer->bin_buffer,

			buffer->bin_buffer_size, ppos, buf, count);

	len = copy_from_iter(buffer->bin_buffer, buffer->bin_buffer_size, from);

out:

	mutex_unlock(&buffer->mutex);

	return len;

	return len ? : -EFAULT;

}



static int __configfs_open_file(struct inode *inode, struct file *file, int type)
@@ -420,16 +420,16 @@ static int configfs_release_bin_file(struct inode *inode, struct file *file) 




const struct file_operations configfs_file_operations = {

	.read		= configfs_read_file,

	.write		= configfs_write_file,

	.read_iter	= configfs_read_iter,

	.write_iter	= configfs_write_iter,

	.llseek		= generic_file_llseek,

	.open		= configfs_open_file,

	.release	= configfs_release,

};



const struct file_operations configfs_bin_file_operations = {

	.read		= configfs_read_bin_file,

	.write		= configfs_write_bin_file,

	.read_iter	= configfs_bin_read_iter,

	.write_iter	= configfs_bin_write_iter,

	.llseek		= NULL,		/* bin file is not seekable */

	.open		= configfs_open_bin_file,

	.release	= configfs_release_bin_file,