Since refcounts do not always have to be a uint16_t, all refcount blocks
and arrays in memory should not have a specific type (thus they become
pointers to void) and for accessing them, two helper functions are used
(a getter and a setter). Those functions are called indirectly through
function pointers in the BDRVQcowState so they may later be exchanged
for different refcount orders.
With the check and repair functions using this function, the refcount
array they are creating will be in big endian byte order; additionally,
using realloc_refcount_array() makes the size of this refcount array
always cluster-aligned. Both combined allow rebuild_refcount_structure()
to drop the bounce buffer which was used to convert parts of the
refcount array to big endian byte order and store them on disk. Instead,
those parts can now be written directly.
Signed-off-by: Max Reitz <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
Reviewed-by: Stefan Hajnoczi <address@hidden>
---
block/qcow2-refcount.c | 122 ++++++++++++++++++++++++++++---------------------
block/qcow2.h | 8 ++++
2 files changed, 79 insertions(+), 51 deletions(-)
@@ -541,7 +561,7 @@ static int QEMU_WARN_UNUSED_RESULT
update_refcount(BlockDriverState *bs,
{
BDRVQcowState *s = bs->opaque;
int64_t start, last, cluster_offset;
- uint16_t *refcount_block = NULL;
+ void *refcount_block = NULL;
int64_t old_table_index = -1;
int ret;
@@ -593,7 +613,7 @@ static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
/* we can update the count and save it */
block_index = cluster_index & (s->refcount_block_size - 1);
- refcount = be16_to_cpu(refcount_block[block_index]);
+ refcount = s->get_refcount(refcount_block, block_index);
if (decrease ? (refcount - addend > refcount)
: (refcount + addend < refcount ||
refcount + addend > s->refcount_max))
@@ -609,7 +629,7 @@ static int QEMU_WARN_UNUSED_RESULT
update_refcount(BlockDriverState *bs,
if (refcount == 0 && cluster_index < s->free_cluster_index) {
s->free_cluster_index = cluster_index;
}
- refcount_block[block_index] = cpu_to_be16(refcount);
+ s->set_refcount(refcount_block, block_index, refcount);
if (refcount == 0 && s->discard_passthrough[type]) {
update_refcount_discard(bs, cluster_offset, s->cluster_size);
@@ -625,8 +645,7 @@ fail:
/* Write last changed block to disk */
if (refcount_block) {
int wret;
- wret = qcow2_cache_put(bs, s->refcount_block_cache,
- (void**) &refcount_block);
+ wret = qcow2_cache_put(bs, s->refcount_block_cache, &refcount_block);
if (wret < 0) {
return ret < 0 ? ret : wret;
}