Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 2f0c6b75 authored by Tejun Heo's avatar Tejun Heo Committed by Greg Kroah-Hartman
Browse files

sysfs: add sysfs_bin_read() 



sysfs bin file handling will be merged into the regular file support.
This patch prepares the read path.

Copy fs/sysfs/bin.c::read() to fs/sysfs/file.c and make it use
sysfs_open_file instead of bin_buffer.  The function is identical copy
except for the use of sysfs_open_file.

The new function is added to sysfs_bin_operations.  This isn't used
yet but will eventually replace fs/sysfs/bin.c.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f9b9a621

fs/sysfs/file.c

+65 −0
Original line number Diff line number Diff line
@@ -139,6 +139,70 @@ static int sysfs_seq_show(struct seq_file *sf, void *v) 
	return 0;

}



/*

 * Read method for bin files.  As reading a bin file can have side-effects,

 * the exact offset and bytes specified in read(2) call should be passed to

 * the read callback making it difficult to use seq_file.  Implement

 * simplistic custom buffering for bin files.

 */

static ssize_t sysfs_bin_read(struct file *file, char __user *userbuf,

			      size_t bytes, loff_t *off)

{

	struct sysfs_open_file *of = sysfs_of(file);

	struct bin_attribute *battr = of->sd->s_bin_attr.bin_attr;

	struct kobject *kobj = of->sd->s_parent->s_dir.kobj;

	int size = file_inode(file)->i_size;

	int count = min_t(size_t, bytes, PAGE_SIZE);

	loff_t offs = *off;

	char *buf;



	if (!bytes)

		return 0;



	if (size) {

		if (offs > size)

			return 0;

		if (offs + count > size)

			count = size - offs;

	}



	buf = kmalloc(count, GFP_KERNEL);

	if (!buf)

		return -ENOMEM;



	/* need of->sd for battr, its parent for kobj */

	mutex_lock(&of->mutex);

	if (!sysfs_get_active(of->sd)) {

		count = -ENODEV;

		mutex_unlock(&of->mutex);

		goto out_free;

	}



	if (battr->read)

		count = battr->read(file, kobj, battr, buf, offs, count);

	else

		count = -EIO;



	sysfs_put_active(of->sd);

	mutex_unlock(&of->mutex);



	if (count < 0)

		goto out_free;



	if (copy_to_user(userbuf, buf, count)) {

		count = -EFAULT;

		goto out_free;

	}



	pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count);



	*off = offs + count;



 out_free:

	kfree(buf);

	return count;

}



/**

 * flush_write_buffer - push buffer to kobject

 * @of: open file
@@ -495,6 +559,7 @@ const struct file_operations sysfs_file_operations = { 
};



const struct file_operations sysfs_bin_operations = {

	.read		= sysfs_bin_read,

	.write		= sysfs_write_file,

	.llseek		= generic_file_llseek,

};