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Re: [Qemu-devel] [PATCH v3 06/22] qcow2: Helper for refcount array reall
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH v3 06/22] qcow2: Helper for refcount array reallocation |
Date: |
Thu, 20 Nov 2014 14:43:38 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 |
On 11/20/2014 10:06 AM, Max Reitz wrote:
> Add a helper function for reallocating a refcount array, independent of
> the refcount order. The newly allocated space is zeroed and the function
> handles failed reallocations gracefully.
>
> The helper function will always align the buffer size to a cluster
> boundary; if storing the refcounts in such an array in big endian byte
> order, this makes it possible to write parts of the array directly as
> refcount blocks into the image file.
>
> Signed-off-by: Max Reitz <address@hidden>
> Reviewed-by: Eric Blake <address@hidden>
Perhaps the changes since v2 warranted removing my earlier R-b to make
sure I review closely?
> ---
> block/qcow2-refcount.c | 135
> +++++++++++++++++++++++++++++++------------------
> 1 file changed, 86 insertions(+), 49 deletions(-)
>
> +static int realloc_refcount_array(BDRVQcowState *s, uint16_t **array,
> + int64_t *size, int64_t new_size)
> +{
> + /* Round to clusters so the array can be directly written to disk */
> + size_t old_byte_size = ROUND_UP(refcount_array_byte_size(s, *size),
> + s->cluster_size);
> + size_t new_byte_size = ROUND_UP(refcount_array_byte_size(s, new_size),
> + s->cluster_size);
> + uint16_t *new_ptr;
> +
> + if (new_byte_size <= old_byte_size) {
> + *size = new_size;
> + return 0;
> + }
> +
> + assert(new_byte_size > 0);
Should this assert be moved before the early exit?
Hmm, that's my only finding, and you did incorporate improvements mostly
to comments or asserts as compared to v2. Moving the assert is small
enough, and not a show-stopper if you leave it in place, so:
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 v3 00/22] qcow2: Support refcount orders != 4, Max Reitz, 2014/11/20
- [Qemu-devel] [PATCH v3 01/22] qcow2: Add two new fields to BDRVQcowState, Max Reitz, 2014/11/20
- [Qemu-devel] [PATCH v3 03/22] qcow2: Use 64 bits for refcount values, Max Reitz, 2014/11/20
- [Qemu-devel] [PATCH v3 04/22] qcow2: Respect error in qcow2_alloc_bytes(), Max Reitz, 2014/11/20
- [Qemu-devel] [PATCH v3 05/22] qcow2: Refcount overflow and qcow2_alloc_bytes(), Max Reitz, 2014/11/20
- [Qemu-devel] [PATCH v3 06/22] qcow2: Helper for refcount array reallocation, Max Reitz, 2014/11/20
- [Qemu-devel] [PATCH v3 02/22] qcow2: Add refcount_width to format-specific info, Max Reitz, 2014/11/20
- [Qemu-devel] [PATCH v3 07/22] qcow2: Helper function for refcount modification, Max Reitz, 2014/11/20