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qcow2-refcount: Snapshot update for zero clusters

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Account for all cluster types in qcow2_update_snapshot_refcounts;
this prevents this function from updating the refcount of unallocated
zero clusters which effectively led to wrong adjustments of the refcount
of cluster 0 (the main qcow2 header). This in turn resulted in images
with (unallocated) zero clusters having a cluster 0 refcount greater
than one after creating a snapshot.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Max Reitz 2013-08-30 10:40:14 +02:00 committed by Kevin Wolf
parent d4ca092a42
commit 8b81a7b6ba
1 changed files with 35 additions and 17 deletions
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52
block/qcow2-refcount.c
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@ -861,11 +861,14 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
}
for(j = 0; j < s->l2_size; j++) {
uint64_t cluster_index;
offset = be64_to_cpu(l2_table[j]);
if (offset != 0) {
old_offset = offset;
offset &= ~QCOW_OFLAG_COPIED;
if (offset & QCOW_OFLAG_COMPRESSED) {
old_offset = offset;
offset &= ~QCOW_OFLAG_COPIED;
switch (qcow2_get_cluster_type(offset)) {
case QCOW2_CLUSTER_COMPRESSED:
nb_csectors = ((offset >> s->csize_shift) &
s->csize_mask) + 1;
if (addend != 0) {
@ -880,8 +883,16 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
}
/* compressed clusters are never modified */
refcount = 2;
} else {
uint64_t cluster_index = (offset & L2E_OFFSET_MASK) >> s->cluster_bits;
break;
case QCOW2_CLUSTER_NORMAL:
case QCOW2_CLUSTER_ZERO:
cluster_index = (offset & L2E_OFFSET_MASK) >> s->cluster_bits;
if (!cluster_index) {
/* unallocated */
refcount = 0;
break;
}
if (addend != 0) {
refcount = update_cluster_refcount(bs, cluster_index, addend,
QCOW2_DISCARD_SNAPSHOT);
@ -893,19 +904,26 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
ret = refcount;
goto fail;
}
}
break;
if (refcount == 1) {
offset |= QCOW_OFLAG_COPIED;
}
if (offset != old_offset) {
if (addend > 0) {
qcow2_cache_set_dependency(bs, s->l2_table_cache,
s->refcount_block_cache);
}
l2_table[j] = cpu_to_be64(offset);
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
case QCOW2_CLUSTER_UNALLOCATED:
refcount = 0;
break;
default:
abort();
}
if (refcount == 1) {
offset |= QCOW_OFLAG_COPIED;
}
if (offset != old_offset) {
if (addend > 0) {
qcow2_cache_set_dependency(bs, s->l2_table_cache,
s->refcount_block_cache);
}
l2_table[j] = cpu_to_be64(offset);
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
}
}