Re: [PATCH 01/15] Introduce noop_llseek()

[Arnd Bergmann]

On Friday 20 November 2009, Jan Blunck wrote:
> On Fri, Nov 20, Jamie Lokier wrote:
> 
> > Jan Blunck wrote:
> > > The noop_llseek() is a llseek() operation that filesystems can use that
> > > don't want to support seeking (leave the file->f_pos untouched) but still
> > > want to let the syscall itself to succeed.
> > 
> > This is weird behaviour: if you want to allow llseek() to succeed but
> > don't really support seeking, why does the device even care about the
> > value of file->f_pos?
> 
> The device itself does not care about it but it is userspace that is expecting
> the seek to succeed. There is a comment in osst that at least there seems to
> be a borken version of tar that wants to seek on the device even it that does
> not have any effect.

Looking at the question from the other side -- if the device and the user
don't care about file->f_pos, what's wrong with calling generic_file_llseek
instead of noop_llseek?

	Arnd <><
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