diff options
Diffstat (limited to 'block/qcow2-cluster.c')
| -rw-r--r-- | block/qcow2-cluster.c | 27 |
1 files changed, 17 insertions, 10 deletions
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 4d888c785f..8411f5e6aa 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -1414,7 +1414,7 @@ int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset) * clusters. */ static int discard_single_l2(BlockDriverState *bs, uint64_t offset, - unsigned int nb_clusters, enum qcow2_discard_type type) + unsigned int nb_clusters, enum qcow2_discard_type type, bool full_discard) { BDRVQcowState *s = bs->opaque; uint64_t *l2_table; @@ -1436,23 +1436,30 @@ static int discard_single_l2(BlockDriverState *bs, uint64_t offset, old_l2_entry = be64_to_cpu(l2_table[l2_index + i]); /* - * Make sure that a discarded area reads back as zeroes for v3 images - * (we cannot do it for v2 without actually writing a zero-filled - * buffer). We can skip the operation if the cluster is already marked - * as zero, or if it's unallocated and we don't have a backing file. + * If full_discard is false, make sure that a discarded area reads back + * as zeroes for v3 images (we cannot do it for v2 without actually + * writing a zero-filled buffer). We can skip the operation if the + * cluster is already marked as zero, or if it's unallocated and we + * don't have a backing file. * * TODO We might want to use bdrv_get_block_status(bs) here, but we're * holding s->lock, so that doesn't work today. + * + * If full_discard is true, the sector should not read back as zeroes, + * but rather fall through to the backing file. */ switch (qcow2_get_cluster_type(old_l2_entry)) { case QCOW2_CLUSTER_UNALLOCATED: - if (!bs->backing_hd) { + if (full_discard || !bs->backing_hd) { continue; } break; case QCOW2_CLUSTER_ZERO: - continue; + if (!full_discard) { + continue; + } + break; case QCOW2_CLUSTER_NORMAL: case QCOW2_CLUSTER_COMPRESSED: @@ -1464,7 +1471,7 @@ static int discard_single_l2(BlockDriverState *bs, uint64_t offset, /* First remove L2 entries */ qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); - if (s->qcow_version >= 3) { + if (!full_discard && s->qcow_version >= 3) { l2_table[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO); } else { l2_table[l2_index + i] = cpu_to_be64(0); @@ -1483,7 +1490,7 @@ static int discard_single_l2(BlockDriverState *bs, uint64_t offset, } int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset, - int nb_sectors, enum qcow2_discard_type type) + int nb_sectors, enum qcow2_discard_type type, bool full_discard) { BDRVQcowState *s = bs->opaque; uint64_t end_offset; @@ -1506,7 +1513,7 @@ int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset, /* Each L2 table is handled by its own loop iteration */ while (nb_clusters > 0) { - ret = discard_single_l2(bs, offset, nb_clusters, type); + ret = discard_single_l2(bs, offset, nb_clusters, type, full_discard); if (ret < 0) { goto fail; } |