On 08.03.2017 03:54, Eric Blake wrote: > qcow2_discard_clusters() is set up to silently ignore sub-cluster > head or tail on unaligned requests. However, it is easy to audit > the various callers: qcow2_snapshot_create() has always passed > aligned data since the call was introduced in 1ebf561; > qcow2_co_pdiscard() has passed aligned clusters since commit > ecdbead taught the block layer the preferred discard alignment (the > block layer can still pass sub-cluster values, but those are > handled directly in qcow2_co_pdiscard()); and qcow2_make_empty() > was fixed to pass aligned clusters in commit a3e1505. Replace > rounding with assertions to hold us to the tighter contract, > eliminating the now-impossible case of an early exit for a > sub-cluster request. > > qcow2_zero_clusters() has always been called with cluster-aligned > arguments from its lone caller qcow2_co_pwrite_zeroes() (like > qcow2_co_pdiscard(), the caller takes care of sub-cluster requests > from the block layer; and qcow2_zero_clusters() would have > misbehaved on unaligned requests), but it deserves the same > assertion for symmetry. > > Signed-off-by: Eric Blake <ebl...@redhat.com> > > --- > v6: avoid assertion on non-cluster-aligned image, use s->cluster_sectors > to avoid a shift, drop R-b > v5: no change > v4: new patch > --- > block/qcow2-cluster.c | 15 ++++++++------- > 1 file changed, 8 insertions(+), 7 deletions(-)
Reviewed-by: Max Reitz <mre...@redhat.com>
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