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[PATCH v4 27/30] qcow2: Assert that expand_zero_clusters_in_l1() does no
From: |
Alberto Garcia |
Subject: |
[PATCH v4 27/30] qcow2: Assert that expand_zero_clusters_in_l1() does not support subclusters |
Date: |
Tue, 17 Mar 2020 19:16:24 +0100 |
This function is only used by qcow2_expand_zero_clusters() to
downgrade a qcow2 image to a previous version. It is however not
possible to downgrade an image with extended L2 entries because older
versions of qcow2 do not have this feature.
Signed-off-by: Alberto Garcia <address@hidden>
---
block/qcow2-cluster.c | 8 +++++++-
tests/qemu-iotests/061 | 6 ++++++
tests/qemu-iotests/061.out | 5 +++++
3 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 1f471db98c..125d2852f6 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -2039,6 +2039,9 @@ static int expand_zero_clusters_in_l1(BlockDriverState
*bs, uint64_t *l1_table,
int ret;
int i, j;
+ /* qcow2_downgrade() is not allowed in images with subclusters */
+ assert(!has_subclusters(s));
+
slice_size2 = s->l2_slice_size * l2_entry_size(s);
n_slices = s->cluster_size / slice_size2;
@@ -2107,7 +2110,8 @@ static int expand_zero_clusters_in_l1(BlockDriverState
*bs, uint64_t *l1_table,
if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) {
if (!bs->backing) {
/* not backed; therefore we can simply deallocate the
- * cluster */
+ * cluster. No need to call set_l2_bitmap(), this
+ * function doesn't support images with subclusters. */
set_l2_entry(s, l2_slice, j, 0);
l2_dirty = true;
continue;
@@ -2178,6 +2182,8 @@ static int expand_zero_clusters_in_l1(BlockDriverState
*bs, uint64_t *l1_table,
} else {
set_l2_entry(s, l2_slice, j, offset);
}
+ /* No need to call set_l2_bitmap() after set_l2_entry() because
+ * this function doesn't support images with subclusters. */
l2_dirty = true;
}
diff --git a/tests/qemu-iotests/061 b/tests/qemu-iotests/061
index 36b040491f..66bfd23179 100755
--- a/tests/qemu-iotests/061
+++ b/tests/qemu-iotests/061
@@ -266,6 +266,12 @@ $QEMU_IMG amend -o "compat=0.10" "$TEST_IMG"
_img_info --format-specific
_check_test_img
+echo
+echo "=== Testing version downgrade with extended L2 entries ==="
+echo
+_make_test_img -o "compat=1.1,extended_l2=on" 64M
+$QEMU_IMG amend -o "compat=0.10" "$TEST_IMG"
+
echo
echo "=== Try changing the external data file ==="
echo
diff --git a/tests/qemu-iotests/061.out b/tests/qemu-iotests/061.out
index 8b3091a412..5d009867a2 100644
--- a/tests/qemu-iotests/061.out
+++ b/tests/qemu-iotests/061.out
@@ -498,6 +498,11 @@ Format specific information:
corrupt: false
No errors were found on the image.
+=== Testing version downgrade with extended L2 entries ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
+qemu-img: Cannot downgrade an image with incompatible features 0x10 set
+
=== Try changing the external data file ===
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
--
2.20.1
- [PATCH v4 08/30] qcow2: Add dummy has_subclusters() function, (continued)
- [PATCH v4 08/30] qcow2: Add dummy has_subclusters() function, Alberto Garcia, 2020/03/17
- [PATCH v4 20/30] qcow2: Add subcluster support to discard_in_l2_slice(), Alberto Garcia, 2020/03/17
- [PATCH v4 19/30] qcow2: Add subcluster support to zero_in_l2_slice(), Alberto Garcia, 2020/03/17
- [PATCH v4 24/30] qcow2: Clear the L2 bitmap when allocating a compressed cluster, Alberto Garcia, 2020/03/17
- [PATCH v4 03/30] qcow2: Add calculate_l2_meta(), Alberto Garcia, 2020/03/17
- [PATCH v4 13/30] qcow2: Add QCow2SubclusterType and qcow2_get_subcluster_type(), Alberto Garcia, 2020/03/17
- [PATCH v4 17/30] qcow2: Add subcluster support to calculate_l2_meta(), Alberto Garcia, 2020/03/17
- [PATCH v4 01/30] qcow2: Make Qcow2AioTask store the full host offset, Alberto Garcia, 2020/03/17
- [PATCH v4 26/30] qcow2: Restrict qcow2_co_pwrite_zeroes() to full clusters only, Alberto Garcia, 2020/03/17
- [PATCH v4 27/30] qcow2: Assert that expand_zero_clusters_in_l1() does not support subclusters,
Alberto Garcia <=
- [PATCH v4 07/30] qcow2: Document the Extended L2 Entries feature, Alberto Garcia, 2020/03/17
- [PATCH v4 30/30] iotests: Add tests for qcow2 images with extended L2 entries, Alberto Garcia, 2020/03/17
- [PATCH v4 28/30] qcow2: Add the 'extended_l2' option and the QCOW2_INCOMPAT_EXTL2 bit, Alberto Garcia, 2020/03/17