static int get_refcount(BlockDriverState *bs, int64_t cluster_index) { BDRVQcowState *s = bs->opaque; int refcount_table_index, block_index; int64_t refcount_block_offset; int ret; uint16_t *refcount_block; uint16_t refcount; refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); if (refcount_table_index >= s->refcount_table_size) return 0; refcount_block_offset = s->refcount_table[refcount_table_index] & REFT_OFFSET_MASK; if (!refcount_block_offset) return 0; ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset, (void**) &refcount_block); if (ret < 0) { return ret; } block_index = cluster_index & ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); refcount = be16_to_cpu(refcount_block[block_index]); ret = qcow2_cache_put(bs, s->refcount_block_cache, (void**) &refcount_block); if (ret < 0) { return ret; } return refcount; }