Re: fiemap is broken for sparse file in ext4?

[Tao Ma]

Hi Eric,
Eric Sandeen wrote:
> Greg Freemyer wrote:
>   
> > On Fri, Jun 11, 2010 at 11:46 AM, Eric Sandeen <sandeen@xxxxxxxxxx> wrote:
> >     
> > > Tao Ma wrote:
> > >
> > >       
> > > > > What are you using to call fiemap?  Here it seems to be working:
> > > > >           
> > > > I just wrote a simple test program by calling ioctl. It is attached.
> > > > btw, you need to call it immediately after dd so that we have a chance
> > > > that ext4 don't have time to allocate extents. ;)
> > > >         
> > > OK I take it back, I do see it.  *cough* too many different filesystems
> > > on this box ... ;)
> > >
> > > Yes, it does look like a bug.
> > >
> > > -Eric
> > >       
> > I'm not clear how this is supposed to work.
> >
> > Is this just a userspace bug in that FIEMAP_FLAG_SYNC is needed in the
> > fiemap call, or is there a kernel bug as well?
> >     
>
> The flag is optional, though maybe filefrag should use it.
>
> Without it, we should get the proper logical offset and a delalloc-flagged
> extent returned
>
>   
> > If fiemap is called with the FIEMAP_FLAG_SYNC flag is there currently a problem?
> >     
>
> yep, we should get one delalloc extent in the results and we don't.
>   
With FIEMAP_FLAG_SYNC set, my test shows that we get one extent without 
dealloc flags. So no problem with it.
We have another different test result? ;)

Regards,
Tao

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