Re: [Qemu-devel] [PATCH v6] qcow2: Buffer L1 table in snapshot refcount update

[Max Reitz <mreitz@redhat.com>]

On 2014-11-11 at 16:27, Max Reitz wrote:
> From: Zhang Haoyu <zhanghy@sangfor.com>
>
> Buffer the active L1 table in qcow2_update_snapshot_refcount() in order
> to prevent in-place conversion of the L1 table buffer in the
> BDRVQcowState to big endian and back, which would lead to data
> corruption if that buffer was accessed concurrently. This should not
> happen but better being safe than sorry.
>
> Signed-off-by: Zhang Haoyu <zhanghy@sangfor.com>
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
> v6 for "snapshot: use local variable to bdrv_pwrite_sync L1 table" (I
> changed the commit message wording to make it more clear what this patch
> does and why we want it).
>
> Changes in v6:
> - Only copy the local buffer back into s->l1_table if we are indeed
>    accessing the local L1 table
> - Use qemu_vfree() instead of g_free()
> ---
>   block/qcow2-refcount.c | 30 ++++++++++++++----------------
>   1 file changed, 14 insertions(+), 16 deletions(-)

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