Re: [PATCH] RDMA/cxgb4: Add default_llseek to debugfs files.

Arnd Bergmann
2010-09-29T19:18:12Z

On Wednesday 29 September 2010 19:19:32 Roland Dreier wrote:
> > @@ -182,6 +182,7 @@ static const struct file_operations qp_debugfs_fops = {
> > .open = qp_open,
> > .release = qp_release,
> > .read = debugfs_read,
> > + .llseek = default_llseek,
> > };
>
> I think this could actually be generic_file_llseek (right, Arnd?).

The main difference between default_llseek and generic_file_llseek
is that default_llseek doesn't care about the maximum file size
of the underlying file system, which is ULONG_MAX on debugfs,
so they are equivalent.

In general, the preferred one is no_llseek for those files where
you know you do not need to seek. If you do, I'd use default_llseek
for character devices and generic_file_llseek for file systems
that set the s_maxbytes.

Arnd