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Date: Sat, 16 Jun 2012 20:01:10 +0100
Message-ID: <CADLo83-T+4W2aUKc=-CEUrOqwCq5aqipt-fK=BBboQVNJ3qcWQ@mail.gmail.com>
From: Chris Rees <utisoft@gmail.com>
To: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl>
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Cc: freebsd-hackers@freebsd.org, Xin LI <d@delphij.net>
Subject: Re: BIO_DELETE equivalent for file on FFS filesystem
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On Jun 14, 2012 5:49 AM, "Wojciech Puchar" <wojtek@wojtek.tensor.gdynia.pl>
wrote:
>>>
>>> file to take 900MB or... can i call some system function to "punch"
>>> holes?
>>
>>
>> I think you can only truncate the file at this time, pretty much like
>> brk() works for memory.
>
>
>
> BAD. suppose i keep windoze VM image on filesystem which takes 10GB but
uses 5GB.
>
> i could write simple program to find out what blocks are unused and
then...do nothing.
>

What if you cp it?

Chris