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qcow2-cluster: Expand zero clusters

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Add functionality for expanding zero clusters. This is necessary for
downgrading the image version to one without zero cluster support.

For non-backed images, this function may also just discard zero clusters
instead of truly expanding them.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Max Reitz 2013-09-03 10:09:52 +02:00 • committed by Kevin Wolf
parent e7108feaac
commit 32b6444d23
3 changed files with 253 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

29
block/qcow2-refcount.c
View file

@ -601,10 +601,10 @@ fail:
* If the return value is non-negative, it is the new refcount of the cluster.
* If it is negative, it is -errno and indicates an error.
*/
static int update_cluster_refcount(BlockDriverState *bs,
int64_t cluster_index,
int addend,
enum qcow2_discard_type type)
int qcow2_update_cluster_refcount(BlockDriverState *bs,
int64_t cluster_index,
int addend,
enum qcow2_discard_type type)
{
BDRVQcowState *s = bs->opaque;
int ret;
@ -733,8 +733,8 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
if (free_in_cluster == 0)
s->free_byte_offset = 0;
if ((offset & (s->cluster_size - 1)) != 0)
update_cluster_refcount(bs, offset >> s->cluster_bits, 1,
QCOW2_DISCARD_NEVER);
qcow2_update_cluster_refcount(bs, offset >> s->cluster_bits, 1,
QCOW2_DISCARD_NEVER);
} else {
offset = qcow2_alloc_clusters(bs, s->cluster_size);
if (offset < 0) {
@ -744,8 +744,8 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
if ((cluster_offset + s->cluster_size) == offset) {
/* we are lucky: contiguous data */
offset = s->free_byte_offset;
update_cluster_refcount(bs, offset >> s->cluster_bits, 1,
QCOW2_DISCARD_NEVER);
qcow2_update_cluster_refcount(bs, offset >> s->cluster_bits, 1,
QCOW2_DISCARD_NEVER);
s->free_byte_offset += size;
} else {
s->free_byte_offset = offset;
@ -754,8 +754,8 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
}
/* The cluster refcount was incremented, either by qcow2_alloc_clusters()
* or explicitly by update_cluster_refcount(). Refcount blocks must be
* flushed before the caller's L2 table updates.
* or explicitly by qcow2_update_cluster_refcount(). Refcount blocks must
* be flushed before the caller's L2 table updates.
*/
qcow2_cache_set_dependency(bs, s->l2_table_cache, s->refcount_block_cache);
return offset;
@ -896,8 +896,9 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
break;
}
if (addend != 0) {
refcount = update_cluster_refcount(bs, cluster_index, addend,
QCOW2_DISCARD_SNAPSHOT);
refcount = qcow2_update_cluster_refcount(bs,
cluster_index, addend,
QCOW2_DISCARD_SNAPSHOT);
} else {
refcount = get_refcount(bs, cluster_index);
}
@ -936,8 +937,8 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
if (addend != 0) {
refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend,
QCOW2_DISCARD_SNAPSHOT);
refcount = qcow2_update_cluster_refcount(bs, l2_offset >>
s->cluster_bits, addend, QCOW2_DISCARD_SNAPSHOT);
} else {
refcount = get_refcount(bs, l2_offset >> s->cluster_bits);
}