Re: [Qemu-devel] [PATCH for-2.0] qcow2: link all L2 meta updates in preallocate()

[Stefan Hajnoczi <stefanha@gmail.com>]

On Tue, Apr 01, 2014 at 11:12:57AM +0200, Stefan Hajnoczi wrote:
> preallocate() only links the first QCowL2Meta's data clusters into the
> L2 table and ignores any chained QCowL2Metas in the linked list.
> 
> Chains of QCowL2Meta structs are built up when contiguous clusters span
> L2 tables.  Each QCowL2Meta describes one L2 table update.  This is a
> rare case in preallocate() but can happen.
> 
> This patch fixes preallocate() by iterating over the whole list of
> QCowL2Metas.  Compare with the qcow2_co_writev() function's
> implementation, which is similar but also also handles request
> dependencies.  preallocate() only performs one allocation at a time so
> there can be no dependencies.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  block/qcow2.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)

Discussed with Kevin and applied to my block tree:
https://github.com/stefanha/qemu/commits/block

Stefan