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List:       qemu-devel
Subject:    Re: [Qemu-devel] [RFC PATCH 14/17] block: support FALLOC_FL_PUNCH_HOLE trimming
From:       Paolo Bonzini <pbonzini () redhat ! com>
Date:       2012-03-09 8:40:46
Message-ID: 4F59C20E.9040402 () redhat ! com
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Il 09/03/2012 09:35, Chris Wedgwood ha scritto:
>> SEEK_HOLE could provide a very simple heuristic to detect preallocated
>> files (unfortunately ext4 does not implement SEEK_HOLE yet).
> 
> SEEK_HOLE is a weird (confusing and no intuitive) API (IMO).  There is
> FIEMAP or whatever it's called which seems somewhat saner.

FIEMAP is a powertool, we need a butter knife only (cit.).

> Simplest still compare the blocks allocated by the file
> to it's length (ie. stat.st_blocks != stat.st_size>>9).

But yes, you're right about this.

Paolo


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