The logic of this function remains pretty much the same, except that
it uses count_contiguous_subclusters(), which combines the logic of
count_contiguous_clusters() / count_contiguous_clusters_unallocated()
and checks individual subclusters.
Signed-off-by: Alberto Garcia <be...@igalia.com>
---
block/qcow2-cluster.c | 136 ++++++++++++++++++++----------------------
block/qcow2.h | 36 +++++------
2 files changed, 80 insertions(+), 92 deletions(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index c6eb480ee8..c10601a828 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -372,66 +372,55 @@ fail:
}
/*
- * Checks how many clusters in a given L2 slice are contiguous in the image
- * file. As soon as one of the flags in the bitmask stop_flags changes compared
- * to the first cluster, the search is stopped and the cluster is not counted
- * as contiguous. (This allows it, for example, to stop at the first compressed
- * cluster which may require a different handling)
+ * Return the number of contiguous subclusters of the exact same type
+ * in a given L2 slice, starting from cluster @l2_index, subcluster
+ * @sc_index. Allocated subclusters are required to be contiguous in
+ * the image file.
+ * At most @nb_clusters are checked (note that this means clusters,
+ * not subclusters).
*/
-static int count_contiguous_clusters(BlockDriverState *bs, int nb_clusters,
- int cluster_size, uint64_t *l2_slice, int l2_index, uint64_t
stop_flags)
+static int count_contiguous_subclusters(BlockDriverState *bs, int nb_clusters,
+ unsigned sc_index, uint64_t *l2_slice,
+ int l2_index)
{
BDRVQcow2State *s = bs->opaque;
- int i;
- QCow2ClusterType first_cluster_type;
- uint64_t mask = stop_flags | L2E_OFFSET_MASK | QCOW_OFLAG_COMPRESSED;
- uint64_t first_entry = get_l2_entry(s, l2_slice, l2_index);
- uint64_t offset = first_entry & mask;
-
- first_cluster_type = qcow2_get_cluster_type(bs, first_entry);
- if (first_cluster_type == QCOW2_CLUSTER_UNALLOCATED) {
- return 0;
+ int i, j, count = 0;
+ uint64_t l2_entry = get_l2_entry(s, l2_slice, l2_index);
+ uint64_t l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index);
+ uint64_t expected_offset = l2_entry & L2E_OFFSET_MASK;
+ bool check_offset = true;
+ QCow2SubclusterType type =
+ qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_index);
+
+ assert(type != QCOW2_SUBCLUSTER_INVALID); /* The caller should check this
*/
+
+ if (type == QCOW2_SUBCLUSTER_COMPRESSED) {
+ /* Compressed clusters are always processed one by one */
+ return s->subclusters_per_cluster - sc_index;
}
- /* must be allocated */
- assert(first_cluster_type == QCOW2_CLUSTER_NORMAL ||
- first_cluster_type == QCOW2_CLUSTER_ZERO_ALLOC);
-
- for (i = 0; i < nb_clusters; i++) {
- uint64_t l2_entry = get_l2_entry(s, l2_slice, l2_index + i) & mask;
- if (offset + (uint64_t) i * cluster_size != l2_entry) {
- break;
- }
+ if (type == QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN ||
+ type == QCOW2_SUBCLUSTER_ZERO_PLAIN) {
+ check_offset = false;
}
- return i;
-}
-
-/*
- * Checks how many consecutive unallocated clusters in a given L2
- * slice have the same cluster type.
- */
-static int count_contiguous_clusters_unallocated(BlockDriverState *bs,
- int nb_clusters,
- uint64_t *l2_slice,
- int l2_index,
- QCow2ClusterType wanted_type)
-{
- BDRVQcow2State *s = bs->opaque;
- int i;
-
- assert(wanted_type == QCOW2_CLUSTER_ZERO_PLAIN ||
- wanted_type == QCOW2_CLUSTER_UNALLOCATED);
for (i = 0; i < nb_clusters; i++) {
- uint64_t entry = get_l2_entry(s, l2_slice, l2_index + i);
- QCow2ClusterType type = qcow2_get_cluster_type(bs, entry);
-
- if (type != wanted_type) {
- break;
+ l2_entry = get_l2_entry(s, l2_slice, l2_index + i);
+ l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i);
+ if (check_offset && expected_offset != (l2_entry & L2E_OFFSET_MASK)) {
+ goto out;
+ }
+ for (j = (i == 0) ? sc_index : 0; j < s->subclusters_per_cluster; j++)
{
+ if (qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, j) != type)
{
+ goto out;
+ }
+ count++;
}
+ expected_offset += s->cluster_size;
}
- return i;
+out:
+ return count;
}
static int coroutine_fn do_perform_cow_read(BlockDriverState *bs,
@@ -515,12 +504,12 @@ int qcow2_get_cluster_offset(BlockDriverState *bs,
uint64_t offset,
QCow2SubclusterType *subcluster_type)
{
BDRVQcow2State *s = bs->opaque;
- unsigned int l2_index;
- uint64_t l1_index, l2_offset, *l2_slice;
- int c;
+ unsigned int l2_index, sc_index;
+ uint64_t l1_index, l2_offset, *l2_slice, l2_bitmap;
+ int sc;
unsigned int offset_in_cluster;
uint64_t bytes_available, bytes_needed, nb_clusters;
- QCow2ClusterType type;
+ QCow2SubclusterType type;
int ret;
offset_in_cluster = offset_into_cluster(s, offset);
@@ -570,7 +559,9 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t
offset,
/* find the cluster offset for the given disk offset */
l2_index = offset_to_l2_slice_index(s, offset);
+ sc_index = offset_to_sc_index(s, offset);
*cluster_offset = get_l2_entry(s, l2_slice, l2_index);
+ l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index);
nb_clusters = size_to_clusters(s, bytes_needed);
/* bytes_needed <= *bytes + offset_in_cluster, both of which are unsigned
@@ -578,9 +569,9 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t
offset,
* true */
assert(nb_clusters <= INT_MAX);
- type = qcow2_get_cluster_type(bs, *cluster_offset);
- if (s->qcow_version < 3 && (type == QCOW2_CLUSTER_ZERO_PLAIN ||
- type == QCOW2_CLUSTER_ZERO_ALLOC)) {
+ type = qcow2_get_subcluster_type(bs, *cluster_offset, l2_bitmap, sc_index);
+ if (s->qcow_version < 3 && (type == QCOW2_SUBCLUSTER_ZERO_PLAIN ||
+ type == QCOW2_SUBCLUSTER_ZERO_ALLOC)) {
qcow2_signal_corruption(bs, true, -1, -1, "Zero cluster entry found"
" in pre-v3 image (L2 offset: %#" PRIx64
", L2 index: %#x)", l2_offset, l2_index);
@@ -588,7 +579,13 @@ int qcow2_get_cluster_offset(BlockDriverState *bs,
uint64_t offset,
goto fail;
}
switch (type) {
- case QCOW2_CLUSTER_COMPRESSED:
+ case QCOW2_SUBCLUSTER_INVALID:
+ qcow2_signal_corruption(bs, true, -1, -1, "Invalid cluster entry found
"
+ " (L2 offset: %#" PRIx64 ", L2 index: %#x)",
+ l2_offset, l2_index);
+ ret = -EIO;
+ goto fail;
+ case QCOW2_SUBCLUSTER_COMPRESSED:
if (has_data_file(bs)) {
qcow2_signal_corruption(bs, true, -1, -1, "Compressed cluster "
"entry found in image with external data "
@@ -598,21 +595,20 @@ int qcow2_get_cluster_offset(BlockDriverState *bs,
uint64_t offset,
goto fail;
}
/* Compressed clusters can only be processed one by one */
- c = 1;
+ sc = s->subclusters_per_cluster - sc_index;
*cluster_offset &= L2E_COMPRESSED_OFFSET_SIZE_MASK;
break;
- case QCOW2_CLUSTER_ZERO_PLAIN:
- case QCOW2_CLUSTER_UNALLOCATED:
- /* how many empty clusters ? */
- c = count_contiguous_clusters_unallocated(bs, nb_clusters,
- l2_slice, l2_index, type);
+ case QCOW2_SUBCLUSTER_ZERO_PLAIN:
+ case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN:
+ sc = count_contiguous_subclusters(bs, nb_clusters, sc_index,
+ l2_slice, l2_index);
*cluster_offset = 0;
break;
- case QCOW2_CLUSTER_ZERO_ALLOC:
- case QCOW2_CLUSTER_NORMAL:
- /* how many allocated clusters ? */
- c = count_contiguous_clusters(bs, nb_clusters, s->cluster_size,
- l2_slice, l2_index, QCOW_OFLAG_ZERO);
+ case QCOW2_SUBCLUSTER_ZERO_ALLOC:
+ case QCOW2_SUBCLUSTER_NORMAL:
+ case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC:
+ sc = count_contiguous_subclusters(bs, nb_clusters, sc_index,
+ l2_slice, l2_index);
*cluster_offset &= L2E_OFFSET_MASK;
if (offset_into_cluster(s, *cluster_offset)) {
qcow2_signal_corruption(bs, true, -1, -1,
@@ -641,7 +637,7 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t
offset,
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
- bytes_available = (int64_t)c * s->cluster_size;
+ bytes_available = ((int64_t)sc + sc_index) << s->subcluster_bits;
out:
if (bytes_available > bytes_needed) {
@@ -654,7 +650,7 @@ out:
assert(bytes_available - offset_in_cluster <= UINT_MAX);
*bytes = bytes_available - offset_in_cluster;
- *subcluster_type = qcow2_cluster_to_subcluster_type(type);
+ *subcluster_type = type;
return 0;
diff --git a/block/qcow2.h b/block/qcow2.h
index 37b7e25989..ae7973a2c2 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -651,27 +651,6 @@ static inline QCow2ClusterType
qcow2_get_cluster_type(BlockDriverState *bs,
}
}
-/* For an image without extended L2 entries, return the
- * QCow2SubclusterType equivalent of a given QCow2ClusterType */
-static inline
-QCow2SubclusterType qcow2_cluster_to_subcluster_type(QCow2ClusterType type)
-{
- switch (type) {
- case QCOW2_CLUSTER_COMPRESSED:
- return QCOW2_SUBCLUSTER_COMPRESSED;
- case QCOW2_CLUSTER_ZERO_PLAIN:
- return QCOW2_SUBCLUSTER_ZERO_PLAIN;
- case QCOW2_CLUSTER_ZERO_ALLOC:
- return QCOW2_SUBCLUSTER_ZERO_ALLOC;
- case QCOW2_CLUSTER_NORMAL:
- return QCOW2_SUBCLUSTER_NORMAL;
- case QCOW2_CLUSTER_UNALLOCATED:
- return QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN;
- default:
- g_assert_not_reached();
- }
-}
-
/* In an image without subsclusters @l2_bitmap is ignored and
* @sc_index must be 0. */
static inline
@@ -720,7 +699,20 @@ QCow2SubclusterType
qcow2_get_subcluster_type(BlockDriverState *bs,
g_assert_not_reached();
}
} else {
- return qcow2_cluster_to_subcluster_type(type);
+ switch (type) {
+ case QCOW2_CLUSTER_COMPRESSED:
+ return QCOW2_SUBCLUSTER_COMPRESSED;
+ case QCOW2_CLUSTER_ZERO_PLAIN:
+ return QCOW2_SUBCLUSTER_ZERO_PLAIN;
+ case QCOW2_CLUSTER_ZERO_ALLOC:
+ return QCOW2_SUBCLUSTER_ZERO_ALLOC;
+ case QCOW2_CLUSTER_NORMAL:
+ return QCOW2_SUBCLUSTER_NORMAL;
+ case QCOW2_CLUSTER_UNALLOCATED:
+ return QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN;
+ default:
+ g_assert_not_reached();
+ }
}
}
--
2.20.1
