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Re: [Qemu-devel] [PATCH v4 10/26] qcow2: Helper function for refcount mo
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH v4 10/26] qcow2: Helper function for refcount modification |
Date: |
Wed, 03 Dec 2014 11:48:56 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 |
On 12/03/2014 06:37 AM, Max Reitz wrote:
> Since refcounts do not always have to be a uint16_t, all refcount blocks
> and arrays in memory should not have a specific type (thus they become
> pointers to void) and for accessing them, two helper functions are used
> (a getter and a setter). Those functions are called indirectly through
> function pointers in the BDRVQcowState so they may later be exchanged
> for different refcount orders.
>
> With the check and repair functions using this function, the refcount
> array they are creating will be in big endian byte order; additionally,
> using realloc_refcount_array() makes the size of this refcount array
> always cluster-aligned. Both combined allow rebuild_refcount_structure()
> to drop the bounce buffer which was used to convert parts of the
> refcount array to big endian byte order and store them on disk. Instead,
> those parts can now be written directly.
>
> Signed-off-by: Max Reitz <address@hidden>
> ---
> block/qcow2-refcount.c | 122
> ++++++++++++++++++++++++++++---------------------
> block/qcow2.h | 8 ++++
> 2 files changed, 79 insertions(+), 51 deletions(-)
>
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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- [Qemu-devel] [PATCH v4 08/26] qcow2: Refcount overflow and qcow2_alloc_bytes(), (continued)
- [Qemu-devel] [PATCH v4 08/26] qcow2: Refcount overflow and qcow2_alloc_bytes(), Max Reitz, 2014/12/03
- [Qemu-devel] [PATCH v4 07/26] qcow2: Respect error in qcow2_alloc_bytes(), Max Reitz, 2014/12/03
- [Qemu-devel] [PATCH v4 09/26] qcow2: Helper for refcount array reallocation, Max Reitz, 2014/12/03
- [Qemu-devel] [PATCH v4 10/26] qcow2: Helper function for refcount modification, Max Reitz, 2014/12/03
- [Qemu-devel] [PATCH v4 11/26] qcow2: More helpers for refcount modification, Max Reitz, 2014/12/03
- [Qemu-devel] [PATCH v4 12/26] qcow2: Open images with refcount order != 4, Max Reitz, 2014/12/03
- [Qemu-devel] [PATCH v4 13/26] qcow2: refcount_order parameter for qcow2_create2, Max Reitz, 2014/12/03
- [Qemu-devel] [PATCH v4 17/26] progress: Allow regressing progress, Max Reitz, 2014/12/03