diff options
Diffstat (limited to 'block/qcow2-cluster.c')
| -rw-r--r-- | block/qcow2-cluster.c | 41 |
1 files changed, 23 insertions, 18 deletions
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 550850b264..71ddb0c462 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -496,10 +496,15 @@ static int coroutine_fn do_perform_cow_write(BlockDriverState *bs, /* - * get_cluster_offset + * get_host_offset * - * For a given offset of the virtual disk, find the cluster type and offset in - * the qcow2 file. The offset is stored in *cluster_offset. + * For a given offset of the virtual disk find the equivalent host + * offset in the qcow2 file and store it in *host_offset. Neither + * offset needs to be aligned to a cluster boundary. + * + * If the cluster is unallocated then *host_offset will be 0. + * If the cluster is compressed then *host_offset will contain the + * complete compressed cluster descriptor. * * On entry, *bytes is the maximum number of contiguous bytes starting at * offset that we are interested in. @@ -511,12 +516,12 @@ static int coroutine_fn do_perform_cow_write(BlockDriverState *bs, * Returns the cluster type (QCOW2_CLUSTER_*) on success, -errno in error * cases. */ -int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset, - unsigned int *bytes, uint64_t *cluster_offset) +int qcow2_get_host_offset(BlockDriverState *bs, uint64_t offset, + unsigned int *bytes, uint64_t *host_offset) { BDRVQcow2State *s = bs->opaque; unsigned int l2_index; - uint64_t l1_index, l2_offset, *l2_slice; + uint64_t l1_index, l2_offset, *l2_slice, l2_entry; int c; unsigned int offset_in_cluster; uint64_t bytes_available, bytes_needed, nb_clusters; @@ -537,7 +542,7 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset, bytes_needed = bytes_available; } - *cluster_offset = 0; + *host_offset = 0; /* seek to the l2 offset in the l1 table */ @@ -570,7 +575,7 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset, /* find the cluster offset for the given disk offset */ l2_index = offset_to_l2_slice_index(s, offset); - *cluster_offset = be64_to_cpu(l2_slice[l2_index]); + l2_entry = be64_to_cpu(l2_slice[l2_index]); nb_clusters = size_to_clusters(s, bytes_needed); /* bytes_needed <= *bytes + offset_in_cluster, both of which are unsigned @@ -578,7 +583,7 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset, * true */ assert(nb_clusters <= INT_MAX); - type = qcow2_get_cluster_type(bs, *cluster_offset); + type = qcow2_get_cluster_type(bs, l2_entry); if (s->qcow_version < 3 && (type == QCOW2_CLUSTER_ZERO_PLAIN || type == QCOW2_CLUSTER_ZERO_ALLOC)) { qcow2_signal_corruption(bs, true, -1, -1, "Zero cluster entry found" @@ -599,42 +604,42 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset, } /* Compressed clusters can only be processed one by one */ c = 1; - *cluster_offset &= L2E_COMPRESSED_OFFSET_SIZE_MASK; + *host_offset = l2_entry & L2E_COMPRESSED_OFFSET_SIZE_MASK; break; case QCOW2_CLUSTER_ZERO_PLAIN: case QCOW2_CLUSTER_UNALLOCATED: /* how many empty clusters ? */ c = count_contiguous_clusters_unallocated(bs, nb_clusters, &l2_slice[l2_index], type); - *cluster_offset = 0; break; case QCOW2_CLUSTER_ZERO_ALLOC: - case QCOW2_CLUSTER_NORMAL: + case QCOW2_CLUSTER_NORMAL: { + uint64_t host_cluster_offset = l2_entry & L2E_OFFSET_MASK; + *host_offset = host_cluster_offset + offset_in_cluster; /* how many allocated clusters ? */ c = count_contiguous_clusters(bs, nb_clusters, s->cluster_size, &l2_slice[l2_index], QCOW_OFLAG_ZERO); - *cluster_offset &= L2E_OFFSET_MASK; - if (offset_into_cluster(s, *cluster_offset)) { + if (offset_into_cluster(s, host_cluster_offset)) { qcow2_signal_corruption(bs, true, -1, -1, "Cluster allocation offset %#" PRIx64 " unaligned (L2 offset: %#" PRIx64 - ", L2 index: %#x)", *cluster_offset, + ", L2 index: %#x)", host_cluster_offset, l2_offset, l2_index); ret = -EIO; goto fail; } - if (has_data_file(bs) && *cluster_offset != offset - offset_in_cluster) - { + if (has_data_file(bs) && *host_offset != offset) { qcow2_signal_corruption(bs, true, -1, -1, "External data file host cluster offset %#" PRIx64 " does not match guest cluster " "offset: %#" PRIx64 - ", L2 index: %#x)", *cluster_offset, + ", L2 index: %#x)", host_cluster_offset, offset - offset_in_cluster, l2_index); ret = -EIO; goto fail; } break; + } default: abort(); } |