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Re: [Qemu-block] [PATCH v3 20/39] qcow2: Update qcow2_get_cluster_offset

From: Max Reitz
Subject: Re: [Qemu-block] [PATCH v3 20/39] qcow2: Update qcow2_get_cluster_offset() to support L2 slices
Date: Wed, 31 Jan 2018 21:24:18 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2

On 2018-01-26 15:59, Alberto Garcia wrote:
> qcow2_get_cluster_offset() checks how many contiguous bytes are
> available at a given offset. The returned number of bytes is limited
> by the amount that can be addressed without having to load more than
> one L2 table.
> Since we'll be loading L2 slices instead of full tables this patch
> changes the limit accordingly using the size of the L2 slice for the
> calculations instead of the full table size.
> One consequence of this is that with small L2 slices operations such
> as 'qemu-img map' will need to iterate in more steps because each
> qcow2_get_cluster_offset() call will potentially return a smaller
> number. However the code is already prepared for that so this doesn't
> break semantics.
> The l2_table variable is also renamed to l2_slice to reflect this, and
> offset_to_l2_index() is replaced with offset_to_l2_slice_index().
> Signed-off-by: Alberto Garcia <address@hidden>
> Reviewed-by: Eric Blake <address@hidden>
> ---
>  block/qcow2-cluster.c | 30 +++++++++++++++---------------
>  1 file changed, 15 insertions(+), 15 deletions(-)

Reviewed-by: Max Reitz <address@hidden>

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