| Message ID | 4e1c4c2994470119889e8f602b9c98f4d3457e8b.1577014346.git.berto@igalia.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add subcluster allocation to qcow2 | expand |
On 22.12.19 12:37, Alberto Garcia wrote: > The L2 bitmap needs to be updated after each write to indicate what > new subclusters are now allocated. > > This needs to happen even if the cluster was already allocated and the > L2 entry was otherwise valid. > > Signed-off-by: Alberto Garcia <berto@igalia.com> > --- > block/qcow2-cluster.c | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > > diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c > index 0a40944667..ed291a4042 100644 > --- a/block/qcow2-cluster.c > +++ b/block/qcow2-cluster.c > @@ -986,6 +986,23 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m) > > set_l2_entry(s, l2_slice, l2_index + i, QCOW_OFLAG_COPIED | > (cluster_offset + (i << s->cluster_bits))); > + > + /* Update bitmap with the subclusters that were just written */ > + if (has_subclusters(s)) { > + unsigned written_from = m->cow_start.offset; > + unsigned written_to = m->cow_end.offset + m->cow_end.nb_bytes ?: > + m->nb_clusters << s->cluster_bits; I suppose we could also calculate both at the beginning of the function (I’m not sure whether the compiler can optimize these calculations to happen only once if we don’t). > + uint64_t l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i); > + int sc; > + for (sc = 0; sc < s->subclusters_per_cluster; sc++) { > + int sc_off = i * s->cluster_size + sc * s->subcluster_size; > + if (sc_off >= written_from && sc_off < written_to) { > + l2_bitmap |= QCOW_OFLAG_SUB_ALLOC(sc); > + l2_bitmap &= ~QCOW_OFLAG_SUB_ZERO(sc); Works, but maybe a QCOW_OFLAG_SUB_MASK(sc) would be better for: l2_bitmap &= ~QCOW_OFLAG_SUB_MASK(sc); l2_bitmap |= QCOW_OFLAG_SUB_ALLOC(sc); Nothing wrong though, so: Reviewed-by: Max Reitz <mreitz@redhat.com> > + } > + } > + set_l2_bitmap(s, l2_slice, l2_index + i, l2_bitmap); > + } > } > > >
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 0a40944667..ed291a4042 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -986,6 +986,23 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m) set_l2_entry(s, l2_slice, l2_index + i, QCOW_OFLAG_COPIED | (cluster_offset + (i << s->cluster_bits))); + + /* Update bitmap with the subclusters that were just written */ + if (has_subclusters(s)) { + unsigned written_from = m->cow_start.offset; + unsigned written_to = m->cow_end.offset + m->cow_end.nb_bytes ?: + m->nb_clusters << s->cluster_bits; + uint64_t l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i); + int sc; + for (sc = 0; sc < s->subclusters_per_cluster; sc++) { + int sc_off = i * s->cluster_size + sc * s->subcluster_size; + if (sc_off >= written_from && sc_off < written_to) { + l2_bitmap |= QCOW_OFLAG_SUB_ALLOC(sc); + l2_bitmap &= ~QCOW_OFLAG_SUB_ZERO(sc); + } + } + set_l2_bitmap(s, l2_slice, l2_index + i, l2_bitmap); + } }
The L2 bitmap needs to be updated after each write to indicate what new subclusters are now allocated. This needs to happen even if the cluster was already allocated and the L2 entry was otherwise valid. Signed-off-by: Alberto Garcia <berto@igalia.com> --- block/qcow2-cluster.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)