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qcow2: Name typedef for cluster type

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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 <mreitz@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-id: 20170507000552.20847-6-eblake@redhat.com
[mreitz: Use the new type in two more places (one of them pulled from
         the next patch)]
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Eric Blake 2017-05-06 19:05:45 -05:00 • committed by Max Reitz
parent 4341df8a83
commit 3ef9521893
3 changed files with 15 additions and 14 deletions
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21
block/qcow2-cluster.c
View file

@ -309,7 +309,7 @@ static int count_contiguous_clusters(int nb_clusters, int cluster_size,
uint64_t *l2_table, uint64_t stop_flags)
{
int i;
int first_cluster_type;
QCow2ClusterType first_cluster_type;
uint64_t mask = stop_flags | L2E_OFFSET_MASK | QCOW_OFLAG_COMPRESSED;
uint64_t first_entry = be64_to_cpu(l2_table[0]);
uint64_t offset = first_entry & mask;
@ -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;
@ -348,7 +348,7 @@ static int count_contiguous_clusters_unallocated(int nb_clusters,
wanted_type == QCOW2_CLUSTER_UNALLOCATED);
for (i = 0; i < nb_clusters; i++) {
uint64_t entry = be64_to_cpu(l2_table[i]);
int type = qcow2_get_cluster_type(entry);
QCow2ClusterType type = qcow2_get_cluster_type(entry);
if (type != wanted_type || entry & L2E_OFFSET_MASK) {
break;
@ -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) {