Am 12.06.2012 16:00, schrieb Paolo Bonzini: > Il 12/06/2012 15:47, Kevin Wolf ha scritto: >> copy_sectors() always uses the sum (cluster_offset + n_start) or >> (start_sect + n_start), so if some value is added to both cluster_offset >> and start_sect, and subtracted from n_start, it's cancelled out anyway. >> >> Signed-off-by: Kevin Wolf <kw...@redhat.com> >> --- >> block/qcow2-cluster.c | 5 ++--- >> 1 files changed, 2 insertions(+), 3 deletions(-) >> >> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c >> index 9aee9fc..763b724 100644 >> --- a/block/qcow2-cluster.c >> +++ b/block/qcow2-cluster.c >> @@ -640,11 +640,10 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, >> QCowL2Meta *m) >> } >> >> if (m->nb_available & (s->cluster_sectors - 1)) { >> - uint64_t end = m->nb_available & ~(uint64_t)(s->cluster_sectors - >> 1); >> cow = true; >> qemu_co_mutex_unlock(&s->lock); >> - ret = copy_sectors(bs, start_sect + end, cluster_offset + (end << >> 9), >> - m->nb_available - end, s->cluster_sectors); >> + ret = copy_sectors(bs, start_sect, cluster_offset, >> + m->nb_available, s->cluster_sectors); > > Do you need to add end to s->cluster_sectors too, so that "start_sect + > n_end" and "n_end - n_start" remain the same?
You mean because n_end is now relative to start_sect instead of start_sect + end, right? I thought about it and I find this code is a bit confusing, but I think you're right that I need to replace n_end as well because it would be wrong for an allocating request than spans multiple clusters. I think this one should be right, would you agree? ret = copy_sectors(bs, start_sect, cluster_offset, m->nb_available, align_offset(m->nb_available, s->cluster_sectors)); The interesting question is why qemu-iotests doesn't catch it. Kevin