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Date:      Sat, 16 Jun 2012 20:01:10 +0100
From:      Chris Rees <utisoft@gmail.com>
To:        Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl>
Cc:        freebsd-hackers@freebsd.org, Xin LI <d@delphij.net>
Subject:   Re: BIO_DELETE equivalent for file on FFS filesystem
Message-ID:  <CADLo83-T%2B4W2aUKc=-CEUrOqwCq5aqipt-fK=BBboQVNJ3qcWQ@mail.gmail.com>
In-Reply-To: <alpine.BSF.2.00.1206140647080.72545@wojtek.tensor.gdynia.pl>
References:  <alpine.BSF.2.00.1205261704590.70782@wojtek.tensor.gdynia.pl> <4FD94240.6060806@delphij.net> <alpine.BSF.2.00.1206140647080.72545@wojtek.tensor.gdynia.pl>

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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



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