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authorAndrey Drobyshev <andrey.drobyshev@virtuozzo.com>2023-07-11 20:25:51 +0300
committerStefan Hajnoczi <stefanha@redhat.com>2023-08-30 07:39:10 -0400
commitc54483b6f45a0c84e230728a1a9e7adf90345e15 (patch)
tree5bf9bacf290a472997dc5cb756125cf5eb92ba9f
parentf187609f27b261702a17f79d20bf252ee0d4f9cd (diff)
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block: add subcluster_size field to BlockDriverInfo
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> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Message-ID: <20230711172553.234055-2-andrey.drobyshev@virtuozzo.com>
-rw-r--r--block.c7
-rw-r--r--block/qcow2.c1
-rw-r--r--include/block/block-common.h5
3 files changed, 13 insertions, 0 deletions
diff --git a/block.c b/block.c
index a307c15..0af890f 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 c51388e..b48cd9c 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 e15395f..df5ffc8 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;