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Re: [Qemu-devel] [PATCH v2 10/21] qcow2: refcount_order parameter for qc
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH v2 10/21] qcow2: refcount_order parameter for qcow2_create2 |
Date: |
Sat, 15 Nov 2014 10:13:04 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 |
On 11/14/2014 06:06 AM, Max Reitz wrote:
> Add a refcount_order parameter to qcow2_create2(), use that value for
> the image header and for calculating the size required for
> preallocation.
>
> For now, always pass 4.
>
> Signed-off-by: Max Reitz <address@hidden>
> ---
> block/qcow2.c | 41 ++++++++++++++++++++++++++++++-----------
> 1 file changed, 30 insertions(+), 11 deletions(-)
>
> @@ -1811,6 +1811,13 @@ static int qcow2_create2(const char *filename, int64_t
> total_size,
> int64_t meta_size = 0;
> uint64_t nreftablee, nrefblocke, nl1e, nl2e;
> int64_t aligned_total_size = align_offset(total_size, cluster_size);
> + int refblock_bits, refblock_size;
> + /* refcount entry size in bytes */
> + double rces = (1 << refcount_order) / 8.;
> +
Maybe worth a comment that absolute precision is not necessary, and that
we are okay that the result gets us to within a fraction of a percent of
the right value.
Reviewed-by: Eric Blake <address@hidden>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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- Re: [Qemu-devel] [PATCH v2 07/21] qcow2: Helper function for refcount modification, (continued)
- [Qemu-devel] [PATCH v2 08/21] qcow2: More helpers for refcount modification, Max Reitz, 2014/11/14
- [Qemu-devel] [PATCH v2 09/21] qcow2: Open images with refcount order != 4, Max Reitz, 2014/11/14
- [Qemu-devel] [PATCH v2 11/21] iotests: Prepare for refcount_width option, Max Reitz, 2014/11/14
- [Qemu-devel] [PATCH v2 12/21] qcow2: Allow creation with refcount order != 4, Max Reitz, 2014/11/14
- [Qemu-devel] [PATCH v2 10/21] qcow2: refcount_order parameter for qcow2_create2, Max Reitz, 2014/11/14
- Re: [Qemu-devel] [PATCH v2 10/21] qcow2: refcount_order parameter for qcow2_create2,
Eric Blake <=
- [Qemu-devel] [PATCH v2 13/21] block: Add opaque value to the amend CB, Max Reitz, 2014/11/14
- [Qemu-devel] [PATCH v2 15/21] qcow2: Use abort() instead of assert(false), Max Reitz, 2014/11/14
- [Qemu-devel] [PATCH v2 16/21] qcow2: Split upgrade/downgrade paths for amend, Max Reitz, 2014/11/14
- [Qemu-devel] [PATCH v2 14/21] qcow2: Use error_report() in qcow2_amend_options(), Max Reitz, 2014/11/14
- [Qemu-devel] [PATCH v2 17/21] qcow2: Use intermediate helper CB for amend, Max Reitz, 2014/11/14
- [Qemu-devel] [PATCH v2 18/21] qcow2: Add function for refcount order amendment, Max Reitz, 2014/11/14
- [Qemu-devel] [PATCH v2 19/21] qcow2: Invoke refcount order amendment function, Max Reitz, 2014/11/14