| Message ID | 20230711172553.234055-2-andrey.drobyshev@virtuozzo.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: align CoR requests to subclusters | expand |
On 11.07.23 20:25, Andrey Drobyshev wrote: > This is going to be used in the subsequent commit as requests alignment > (in particular, during copy-on-read). This value only makes sense for > the formats which support subclusters (currently QCOW2 only). If this > field isn't set by driver's own bdrv_get_info() implementation, we > simply set it equal to the cluster size thus treating each cluster as > having a single subcluster. > > Reviewed-by: Eric Blake<eblake@redhat.com> > Reviewed-by: Denis V. Lunev<den@openvz.org> > Signed-off-by: Andrey Drobyshev<andrey.drobyshev@virtuozzo.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
diff --git a/block.c b/block.c index a307c151a8..0af890f647 100644 --- a/block.c +++ b/block.c @@ -6480,6 +6480,13 @@ int coroutine_fn bdrv_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) } memset(bdi, 0, sizeof(*bdi)); ret = drv->bdrv_co_get_info(bs, bdi); + if (bdi->subcluster_size == 0) { + /* + * If the driver left this unset, subclusters are not supported. + * Then it is safe to treat each cluster as having only one subcluster. + */ + bdi->subcluster_size = bdi->cluster_size; + } if (ret < 0) { return ret; } diff --git a/block/qcow2.c b/block/qcow2.c index c51388e99d..b48cd9ce63 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -5197,6 +5197,7 @@ qcow2_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) { BDRVQcow2State *s = bs->opaque; bdi->cluster_size = s->cluster_size; + bdi->subcluster_size = s->subcluster_size; bdi->vm_state_offset = qcow2_vm_state_offset(s); bdi->is_dirty = s->incompatible_features & QCOW2_INCOMPAT_DIRTY; return 0; diff --git a/include/block/block-common.h b/include/block/block-common.h index e15395f2cb..df5ffc8d09 100644 --- a/include/block/block-common.h +++ b/include/block/block-common.h @@ -132,6 +132,11 @@ typedef struct BlockZoneWps { typedef struct BlockDriverInfo { /* in bytes, 0 if irrelevant */ int cluster_size; + /* + * A fraction of cluster_size, if supported (currently QCOW2 only); if + * disabled or unsupported, set equal to cluster_size. + */ + int subcluster_size; /* offset at which the VM state can be saved (0 if not possible) */ int64_t vm_state_offset; bool is_dirty;