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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 8:31:31
Message-ID: 4F59BFE3.4070907 () redhat ! com
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Il 09/03/2012 09:20, Chris Wedgwood ha scritto:
> for preallocated files this will punch holes all over the place and
> reallocation will cause fragmentation (guests will free and reallocat
> blocks normally)

SEEK_HOLE could provide a very simple heuristic to detect preallocated
files (unfortunately ext4 does not implement SEEK_HOLE yet).

> xfs has a mechanism to convert to unwritten extents that would avoid
> that, but it's not implemented in other filesystems

Interesting, thanks!

Paolo

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