Re: [PATCH 4/4] NFSD: Implement SEEK

[Anna Schumaker <bjschuma@netapp.com>]

On Tue 29 Oct 2013 03:35:58 AM EDT, Christoph Hellwig wrote:
> On Mon, Oct 28, 2013 at 10:57:26AM -0400, Anna Schumaker wrote:
>> This patch adds in the SEEK operation used by clients doing an llseek on
>> a file to find either hole or data sections in a file.  I'm faking the
>> "allocated" status right now, since I haven't quite figured out how to
>> tell if a range is allocated on disk yet.
>>
>> This patch is missing correctly determining the "allocated" status of
>> the HOLE / DATA range.  I expect I'll need to learn all about how fiemap
>> works before properly setting these values.
>
> What is the definition of allocated in this context?  Specificly how
> does it different from meaning of allocated as used by SEEK_DATA?

 From what I can tell, I think the allocated flag will just tell the 
clients if all the blocks exist on disk or not.  Is there a way to have 
a hole with allocated blocks?  Or maybe it's supposed to represent 
partially allocated blocks?  I checked the draft, and it doesn't 
actually say what they expect allocated to represent...

>
> Going out to fiemap is something we should absolutely avoid.
>