diff options
| -rw-r--r-- | block/qcow2-cluster.c | 38 |
1 files changed, 28 insertions, 10 deletions
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index c8c85d224a..7b059908a0 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -246,28 +246,44 @@ fail: return ret; } +/* + * Checks how many clusters in a given L2 table 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) + */ static int count_contiguous_clusters(uint64_t nb_clusters, int cluster_size, - uint64_t *l2_table, uint64_t start, uint64_t mask) + uint64_t *l2_table, uint64_t start, uint64_t stop_flags) { int i; - uint64_t offset = be64_to_cpu(l2_table[0]) & ~mask; + uint64_t mask = stop_flags | L2E_OFFSET_MASK; + uint64_t offset = be64_to_cpu(l2_table[0]) & mask; if (!offset) return 0; - for (i = start; i < start + nb_clusters; i++) - if (offset + (uint64_t) i * cluster_size != (be64_to_cpu(l2_table[i]) & ~mask)) + for (i = start; i < start + nb_clusters; i++) { + uint64_t l2_entry = be64_to_cpu(l2_table[i]) & mask; + if (offset + (uint64_t) i * cluster_size != l2_entry) { break; + } + } return (i - start); } static int count_contiguous_free_clusters(uint64_t nb_clusters, uint64_t *l2_table) { - int i = 0; + int i; - while(nb_clusters-- && l2_table[i] == 0) - i++; + for (i = 0; i < nb_clusters; i++) { + int type = qcow2_get_cluster_type(be64_to_cpu(l2_table[i])); + + if (type != QCOW2_CLUSTER_UNALLOCATED) { + break; + } + } return i; } @@ -444,7 +460,7 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset, case QCOW2_CLUSTER_NORMAL: /* how many allocated clusters ? */ c = count_contiguous_clusters(nb_clusters, s->cluster_size, - &l2_table[l2_index], 0, QCOW_OFLAG_COPIED); + &l2_table[l2_index], 0, QCOW_OFLAG_COMPRESSED); *cluster_offset &= L2E_OFFSET_MASK; break; } @@ -696,7 +712,8 @@ static int count_cow_clusters(BDRVQcowState *s, int nb_clusters, while (i < nb_clusters) { i += count_contiguous_clusters(nb_clusters - i, s->cluster_size, - &l2_table[l2_index], i, 0); + &l2_table[l2_index], i, + QCOW_OFLAG_COPIED | QCOW_OFLAG_COMPRESSED); if ((i >= nb_clusters) || be64_to_cpu(l2_table[l2_index + i])) { break; } @@ -854,7 +871,8 @@ again: if (cluster_offset & QCOW_OFLAG_COPIED) { /* We keep all QCOW_OFLAG_COPIED clusters */ keep_clusters = count_contiguous_clusters(nb_clusters, s->cluster_size, - &l2_table[l2_index], 0, 0); + &l2_table[l2_index], 0, + QCOW_OFLAG_COPIED); assert(keep_clusters <= nb_clusters); nb_clusters -= keep_clusters; } else { |