Re: XFS capacity leak with dmapi

[Vlad Apostolov <vapo@sgi.com>]

John Groves wrote:
> Vlad, I've tried to send this via linux-xfs, but for some reason my 
> posts aren't going through (although I receive messages from it every 
> day).  Any ideas on this?
>
> We have an application that uses DMAPI, and we've been chasing an XFS 
> filesystem capacity leak for a week or two.  Here is the scenario:
>
> In some cases we initially create sparse files - normal open with 
> O_CREAT and than an ftruncate to the desired size. 
>
> If we subsequently fill the files via dm_write_invis(), and then 
> remove/unlink the files, XFS does not appear to free up the capacity 
> that was allocated when the file was made non-sparse via 
> dm_write_invis().  Repeating this sequence enough times results in a 
> full filesystem.
>
> If we use write() to fill the file (after creating it as sparse), 
> remove/unlink appears to work properly, and capacity does not appear 
> to be leaked.  We've seen this on several test systems; the current 
> one is 2.6.22-rc4, which I think is current as to the SGI cvs tree (or 
> very nearly so).
>
> Can anybody shed light on this?
>
> Thanks,
> John Groves
Hi John,

I will investigate this problem but at the moment I can't immediately jump
on it. I am copying the email to linux-xfs list in case if someone could
answer it straightaway.

Regards,
Vlad