Although it doesn't add all that much type safety (this is C, after
all), it does add a bit of legibility to use the name QCow2ClusterType
instead of a plain int.
In particular, qcow2_get_cluster_offset() has an overloaded return
type; a QCow2ClusterType on success, and -errno on failure; keeping
the cluster type in a separate variable makes it slightly easier for
the next patch to make further computations based on the type.
Suggested-by: Max Reitz <mre...@redhat.com>
Signed-off-by: Eric Blake <ebl...@redhat.com>
---
v13: new patch
---
block/qcow2.h | 6 +++---
block/qcow2-cluster.c | 17 +++++++++--------
block/qcow2-refcount.c | 2 +-
3 files changed, 13 insertions(+), 12 deletions(-)
diff --git a/block/qcow2.h b/block/qcow2.h
index 8731f24..c148bbc 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -349,12 +349,12 @@ typedef struct QCowL2Meta
QLIST_ENTRY(QCowL2Meta) next_in_flight;
} QCowL2Meta;
-enum {
+typedef enum QCow2ClusterType {
QCOW2_CLUSTER_UNALLOCATED,
QCOW2_CLUSTER_NORMAL,
QCOW2_CLUSTER_COMPRESSED,
QCOW2_CLUSTER_ZERO
-};
+} QCow2ClusterType;
typedef enum QCow2MetadataOverlap {
QCOW2_OL_MAIN_HEADER_BITNR = 0,
@@ -443,7 +443,7 @@ static inline uint64_t
qcow2_max_refcount_clusters(BDRVQcow2State *s)
return QCOW_MAX_REFTABLE_SIZE >> s->cluster_bits;
}
-static inline int qcow2_get_cluster_type(uint64_t l2_entry)
+static inline QCow2ClusterType qcow2_get_cluster_type(uint64_t l2_entry)
{
if (l2_entry & QCOW_OFLAG_COMPRESSED) {
return QCOW2_CLUSTER_COMPRESSED;
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index f3bfce6..ed78a30 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -340,7 +340,7 @@ static int count_contiguous_clusters(int nb_clusters, int
cluster_size,
*/
static int count_contiguous_clusters_unallocated(int nb_clusters,
uint64_t *l2_table,
- int wanted_type)
+ QCow2ClusterType wanted_type)
{
int i;
@@ -500,6 +500,7 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t
offset,
int l1_bits, c;
unsigned int offset_in_cluster;
uint64_t bytes_available, bytes_needed, nb_clusters;
+ QCow2ClusterType type;
int ret;
offset_in_cluster = offset_into_cluster(s, offset);
@@ -522,13 +523,13 @@ int qcow2_get_cluster_offset(BlockDriverState *bs,
uint64_t offset,
l1_index = offset >> l1_bits;
if (l1_index >= s->l1_size) {
- ret = QCOW2_CLUSTER_UNALLOCATED;
+ type = QCOW2_CLUSTER_UNALLOCATED;
goto out;
}
l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
if (!l2_offset) {
- ret = QCOW2_CLUSTER_UNALLOCATED;
+ type = QCOW2_CLUSTER_UNALLOCATED;
goto out;
}
@@ -557,8 +558,8 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t
offset,
* true */
assert(nb_clusters <= INT_MAX);
- ret = qcow2_get_cluster_type(*cluster_offset);
- switch (ret) {
+ type = qcow2_get_cluster_type(*cluster_offset);
+ switch (type) {
case QCOW2_CLUSTER_COMPRESSED:
/* Compressed clusters can only be processed one by one */
c = 1;
@@ -633,7 +634,7 @@ out:
assert(bytes_available - offset_in_cluster <= UINT_MAX);
*bytes = bytes_available - offset_in_cluster;
- return ret;
+ return type;
fail:
qcow2_cache_put(bs, s->l2_table_cache, (void **)&l2_table);
@@ -891,7 +892,7 @@ static int count_cow_clusters(BDRVQcow2State *s, int
nb_clusters,
for (i = 0; i < nb_clusters; i++) {
uint64_t l2_entry = be64_to_cpu(l2_table[l2_index + i]);
- int cluster_type = qcow2_get_cluster_type(l2_entry);
+ QCow2ClusterType cluster_type = qcow2_get_cluster_type(l2_entry);
switch(cluster_type) {
case QCOW2_CLUSTER_NORMAL:
@@ -1757,7 +1758,7 @@ static int expand_zero_clusters_in_l1(BlockDriverState
*bs, uint64_t *l1_table,
for (j = 0; j < s->l2_size; j++) {
uint64_t l2_entry = be64_to_cpu(l2_table[j]);
int64_t offset = l2_entry & L2E_OFFSET_MASK;
- int cluster_type = qcow2_get_cluster_type(l2_entry);
+ QCow2ClusterType cluster_type = qcow2_get_cluster_type(l2_entry);
bool preallocated = offset != 0;
if (cluster_type != QCOW2_CLUSTER_ZERO) {
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 908dbe5..e639b34 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -1640,7 +1640,7 @@ static int check_oflag_copied(BlockDriverState *bs,
BdrvCheckResult *res,
for (j = 0; j < s->l2_size; j++) {
uint64_t l2_entry = be64_to_cpu(l2_table[j]);
uint64_t data_offset = l2_entry & L2E_OFFSET_MASK;
- int cluster_type = qcow2_get_cluster_type(l2_entry);
+ QCow2ClusterType cluster_type = qcow2_get_cluster_type(l2_entry);
if ((cluster_type == QCOW2_CLUSTER_NORMAL) ||
((cluster_type == QCOW2_CLUSTER_ZERO) && (data_offset != 0))) {
--
2.9.3
