1. 根目录:
2. fs
3. sysfs
4. bin.c

/*
 * fs/sysfs/bin.c - sysfs binary file implementation
 *
 * Copyright (c) 2003 Patrick Mochel
 * Copyright (c) 2003 Matthew Wilcox
 * Copyright (c) 2004 Silicon Graphics, Inc.
 * Copyright (c) 2007 SUSE Linux Products GmbH
 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
 *
 * This file is released under the GPLv2.
 *
 * Please see Documentation/filesystems/sysfs.txt for more information.
 */

#undef DEBUG

#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/mm.h>

#include <asm/uaccess.h>

#include "sysfs.h"

/*
 * There's one bin_buffer for each open file.
 *
 * filp->private_data points to bin_buffer and
 * sysfs_dirent->s_bin_attr.buffers points to a the bin_buffer s
 * sysfs_dirent->s_bin_attr.buffers is protected by sysfs_bin_lock
 */
static DEFINE_MUTEX(sysfs_bin_lock);

struct bin_buffer {
	struct mutex			mutex;
	void				*buffer;
	int				mmapped;
	const struct vm_operations_struct *vm_ops;
	struct file			*file;
	struct hlist_node		list;
};

static int
fill_read(struct file *file, char *buffer, loff_t off, size_t count)
{
	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
	struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
	struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
	int rc;

	/* need attr_sd for attr, its parent for kobj */
	if (!sysfs_get_active(attr_sd))
		return -ENODEV;

	rc = -EIO;
	if (attr->read)
		rc = attr->read(file, kobj, attr, buffer, off, count);

	sysfs_put_active(attr_sd);

	return rc;
}

static ssize_t
read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
{
	struct bin_buffer *bb = file->private_data;
	int size = file->f_path.dentry->d_inode->i_size;
	loff_t offs = *off;
	int count = min_t(size_t, bytes, PAGE_SIZE);
	char *temp;

	if (!bytes)
		return 0;

	if (size) {
		if (offs > size)
			return 0;
		if (offs + count > size)
			count = size - offs;
	}

	temp = kmalloc(count, GFP_KERNEL);
	if (!temp)
		return -ENOMEM;

	mutex_lock(&bb->mutex);

	count = fill_read(file, bb->buffer, offs, count);
	if (count < 0) {
		mutex_unlock(&bb->mutex);
		goto out_free;
	}

	memcpy(temp, bb->buffer, count);

	mutex_unlock(&bb->mutex);

	if (copy_to_user(userbuf, temp, count)) {
		count = -EFAULT;
		goto out_free;
	}

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

	*off = offs + count;

 out_free:
	kfree(temp);
	return count;
}

static int
flush_write(struct file *file, char *buffer, loff_t offset, size_t count)
{
	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
	struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
	struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
	int rc;

	/* need attr_sd for attr, its parent for kobj */
	if (!sysfs_get_active(attr_sd))
		return -ENODEV;

	rc = -EIO;
	if (attr->write)
		rc = attr->write(file, kobj, attr, buffer, offset, count);

	sysfs_put_active(attr_sd);

	return rc;
}

static ssize_t write(struct file *file, const char __user *userbuf,
		     size_t bytes, loff_t *off)
{
	struct bin_buffer *bb = file->private_data;
	int size = file->f_path.dentry->d_inode->i_size;
	loff_t offs = *off;
	int count = min_t(size_t, bytes, PAGE_SIZE);
	char *temp;

	if (!bytes)
		return 0;

	if (size) {
		if (offs > size)
			return 0;
		if (offs + count > size)
			count = size - offs;
	}

	temp = memdup_user(userbuf, count);
	if (IS_ERR(temp))
		return PTR_ERR(temp);

	mutex_lock(&bb->mutex);

	memcpy(bb->buffer, temp, count);

	count = flush_write(file, bb->buffer, offs, count);
	mutex_unlock(&bb->mutex);

	if (count > 0)
		*off = offs + count;

	kfree(temp);
	return count;
}

static void bin_vma_open(struct vm_area_struct *vma)
{
	struct file *file = vma->vm_file;
	struct bin_buffer *bb = file->private_data;
	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;

	if (!bb->vm_ops)
		return;

	if (!sysfs_get_active(attr_sd))
		return;

	if (bb->vm_ops->open)
		bb->vm_ops->open(vma);

	sysfs_put_active(attr_sd);
}

static int bin_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
	struct file *file = vma->vm_file;
	struct bin_buffer *bb = file->private_data;
	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
	int ret;

	if (!bb->vm_ops)
		return VM_FAULT_SIGBUS;

	if (!sysfs_get_active(attr_sd))
		return VM_FAULT_SIGBUS;

	ret = VM_FAULT_SIGBUS;
	if (bb->vm_ops->fault)
		ret = bb->vm_ops->fault(vma, vmf);

	sysfs_put_active(attr_sd);
	return ret;
}

static int bin_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
	struct file *file = vma->vm_file;
	struct bin_buffer *bb = file->private_data;
	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
	int ret;

	if (!bb->vm_ops)
		return VM_FAULT_SIGBUS;

	if (!sysfs_get_active(attr_sd))
		return VM_FAULT_SIGBUS;

	ret = 0;
	if (bb->vm_ops->page_mkwrite)
		ret = bb->vm_ops->page_mkwrite(vma, vmf);

	sysfs_put_active(attr_sd);
	return ret;
}

static int bin_access(struct vm_area_struct *vma, unsigned long addr,
		  void *buf, int len, int write)
{
	struct file *file = vma->vm_file;
	struct bin_buffer *bb = file->private_data;
	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
	int ret;

	if (!bb->vm_ops)
		return -EINVAL;

	if (!sysfs_get_active(attr_sd))
		return -EINVAL;

	ret = -EINVAL;
	if (bb->vm_ops->access)
		ret = bb->vm_ops->access(vma, addr, buf, len, write);

	sysfs_put_active(attr_sd);
	return ret;
}

#ifdef CONFIG_NUMA
static int bin_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
{
	struct file *file = vma->vm_file;
	struct bin_buffer *bb = file->private_data;
	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
	int ret;

	if (!bb->vm_ops)
		return 0;

	if (!sysfs_get_active(attr_sd))
		return -EINVAL;

	ret = 0;
	if (bb->vm_ops->set_policy)
		ret = bb->vm_ops->set_policy(vma, new);

	sysfs_put_active(attr_sd);
	return ret;
}

static struct mempolicy *bin_get_policy(struct vm_area_struct *vma,
					unsigned long addr)
{
	struct file *file = vma->vm_file;
	struct bin_buffer *bb = file->private_data;
	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
	struct mempolicy *pol;

	if (!bb->vm_ops)
		return vma->vm_policy;

	if (!sysfs_get_active(attr_sd))
		return vma->vm_policy;

	pol = vma->vm_policy;
	if (bb->vm_ops->get_policy)
		pol = bb->vm_ops->get_policy(vma, addr);

	sysfs_put_active(attr_sd);
	return pol;
}

static int bin_migrate(struct vm_area_struct *vma, const nodemask_t *from,
			const nodemask_t *to, unsigned long flags)
{
	struct file *file = vma->vm_file;
	struct bin_buffer *bb = file->private_data;
	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
	int ret;

	if (!bb->vm_ops)
		return 0;

	if (!sysfs_get_active(attr_sd))
		return 0;

	ret = 0;
	if (bb->vm_ops->migrate)
		ret = bb->vm_ops->migrate(vma, from, to, flags);

	sysfs_put_active(attr_sd);
	return ret;
}
#endif

static const struct vm_operations_struct bin_vm_ops = {
	.open		= bin_vma_open,
	.fault		= bin_fault,
	.page_mkwrite	= bin_page_mkwrite,
	.access		= bin_access,
#ifdef CONFIG_NUMA
	.set_policy	= bin_set_policy,
	.get_policy	= bin_get_policy,
	.migrate	= bin_migrate,
#endif
};

static int mmap(struct file *file, struct vm_area_struct *vma)
{
	struct bin_buffer *bb = file->private_data;
	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
	struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
	struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
	int rc;

	mutex_lock(&bb->mutex);

	/* need attr_sd for attr, its parent for kobj */
	rc = -ENODEV;
	if (!sysfs_get_active(attr_sd))
		goto out_unlock;

	rc = -EINVAL;
	if (!attr->mmap)
		goto out_put;

	rc = attr->mmap(file, kobj, attr, vma);
	if (rc)
		goto out_put;

	/*
	 * PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
	 * to satisfy versions of X which crash if the mmap fails: that
	 * substitutes a new vm_file, and we don't then want bin_vm_ops.
	 */
	if (vma->vm_file != file)
		goto out_put;

	rc = -EINVAL;
	if (bb->mmapped && bb->vm_ops != vma->vm_ops)
		goto out_put;

	/*
	 * It is not possible to successfully wrap close.
	 * So error if someone is trying to use close.
	 */
	rc = -EINVAL;
	if (vma->vm_ops && vma->vm_ops->close)
		goto out_put;

	rc = 0;
	bb->mmapped = 1;
	bb->vm_ops = vma->vm_ops;
	vma->vm_ops = &bin_vm_ops;
out_put:
	sysfs_put_active(attr_sd);
out_unlock:
	mutex_unlock(&bb->mutex);

	return rc;
}

static int open(struct inode * inode, struct file * file)
{
	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
	struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
	struct bin_buffer *bb = NULL;
	int error;

	/* binary file operations requires both @sd and its parent */
	if (!sysfs_get_active(attr_sd))
		return -ENODEV;

	error = -EACCES;
	if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
		goto err_out;
	if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
		goto err_out;

	error = -ENOMEM;
	bb = kzalloc(sizeof(*bb), GFP_KERNEL);
	if (!bb)
		goto err_out;

	bb->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
	if (!bb->buffer)
		goto err_out;

	mutex_init(&bb->mutex);
	bb->file = file;
	file->private_data = bb;

	mutex_lock(&sysfs_bin_lock);
	hlist_add_head(&bb->list, &attr_sd->s_bin_attr.buffers);
	mutex_unlock(&sysfs_bin_lock);

	/* open succeeded, put active references */
	sysfs_put_active(attr_sd);
	return 0;

 err_out:
	sysfs_put_active(attr_sd);
	kfree(bb);
	return error;
}

static int release(struct inode * inode, struct file * file)
{
	struct bin_buffer *bb = file->private_data;

	mutex_lock(&sysfs_bin_lock);
	hlist_del(&bb->list);
	mutex_unlock(&sysfs_bin_lock);

	kfree(bb->buffer);
	kfree(bb);
	return 0;
}

const struct file_operations bin_fops = {
	.read		= read,
	.write		= write,
	.mmap		= mmap,
	.llseek		= generic_file_llseek,
	.open		= open,
	.release	= release,
};


void unmap_bin_file(struct sysfs_dirent *attr_sd)
{
	struct bin_buffer *bb;
	struct hlist_node *tmp;

	if (sysfs_type(attr_sd) != SYSFS_KOBJ_BIN_ATTR)
		return;

	mutex_lock(&sysfs_bin_lock);

	hlist_for_each_entry(bb, tmp, &attr_sd->s_bin_attr.buffers, list) {
		struct inode *inode = bb->file->f_path.dentry->d_inode;

		unmap_mapping_range(inode->i_mapping, 0, 0, 1);
	}

	mutex_unlock(&sysfs_bin_lock);
}

/**
 *	sysfs_create_bin_file - create binary file for object.
 *	@kobj:	object.
 *	@attr:	attribute descriptor.
 */

int sysfs_create_bin_file(struct kobject *kobj,
			  const struct bin_attribute *attr)
{
	BUG_ON(!kobj || !kobj->sd || !attr);

	return sysfs_add_file(kobj->sd, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
}


/**
 *	sysfs_remove_bin_file - remove binary file for object.
 *	@kobj:	object.
 *	@attr:	attribute descriptor.
 */

void sysfs_remove_bin_file(struct kobject *kobj,
			   const struct bin_attribute *attr)
{
	sysfs_hash_and_remove(kobj->sd, NULL, attr->attr.name);
}

EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);