/**
* sysfs_write_file - write an attribute
* @file: file pointer
* @user_buf: data to write
* @count: number of bytes
* @ppos: starting offset
*
* Copy data in from userland and pass it to the matching
* sysfs_ops->store() by invoking flush_write_buffer().
*
* There is no easy way for us to know if userspace is only doing a partial
* write, so we don't support them. We expect the entire buffer to come on
* the first write. Hint: if you're writing a value, first read the file,
* modify only the the value you're changing, then write entire buffer
* back.
*/
static ssize_t sysfs_write_file(struct file *file, const char __user *user_buf,
size_t count, loff_t *ppos)
{
struct sysfs_open_file *of = sysfs_of(file);
ssize_t len = min_t(size_t, count, PAGE_SIZE);
loff_t size = file_inode(file)->i_size;
char *buf;
if (sysfs_is_bin(of->sd) && size) {
if (size <= *ppos)
return 0;
len = min_t(ssize_t, len, size - *ppos);
}
if (!len)
return 0;
buf = kmalloc(len + 1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
if (copy_from_user(buf, user_buf, len)) {
len = -EFAULT;
goto out_free;
}
buf[len] = '\0'; /* guarantee string termination */
len = flush_write_buffer(of, buf, *ppos, len);
if (len > 0)
*ppos += len;
out_free:
kfree(buf);
return len;
}
/*
* 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_attr.bin_attr;
struct kobject *kobj = of->sd->s_parent->s_dir.kobj;
loff_t 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;
}
static void sysfs_bin_vma_open(struct vm_area_struct *vma)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
if (!of->vm_ops)
return;
if (!sysfs_get_active(of->sd))
return;
if (of->vm_ops->open)
of->vm_ops->open(vma);
sysfs_put_active(of->sd);
}
static int sysfs_bin_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return VM_FAULT_SIGBUS;
if (!sysfs_get_active(of->sd))
return VM_FAULT_SIGBUS;
ret = VM_FAULT_SIGBUS;
if (of->vm_ops->fault)
ret = of->vm_ops->fault(vma, vmf);
sysfs_put_active(of->sd);
return ret;
}
static int sysfs_bin_access(struct vm_area_struct *vma, unsigned long addr,
void *buf, int len, int write)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return -EINVAL;
if (!sysfs_get_active(of->sd))
return -EINVAL;
ret = -EINVAL;
if (of->vm_ops->access)
ret = of->vm_ops->access(vma, addr, buf, len, write);
sysfs_put_active(of->sd);
return ret;
}
static int sysfs_bin_page_mkwrite(struct vm_area_struct *vma,
struct vm_fault *vmf)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return VM_FAULT_SIGBUS;
if (!sysfs_get_active(of->sd))
return VM_FAULT_SIGBUS;
ret = 0;
if (of->vm_ops->page_mkwrite)
ret = of->vm_ops->page_mkwrite(vma, vmf);
else
file_update_time(file);
sysfs_put_active(of->sd);
return ret;
}
return -EINVAL;
ret = -EINVAL;
if (of->vm_ops->access)
ret = of->vm_ops->access(vma, addr, buf, len, write);
sysfs_put_active(of->sd);
return ret;
}
#ifdef CONFIG_NUMA
static int sysfs_bin_set_policy(struct vm_area_struct *vma,
struct mempolicy *new)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return 0;
if (!sysfs_get_active(of->sd))
return -EINVAL;
ret = 0;
if (of->vm_ops->set_policy)
ret = of->vm_ops->set_policy(vma, new);
sysfs_put_active(of->sd);
return ret;
}