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[PATCH v11 33/34] qcow2: Assert that expand_zero_clusters_in_l1() does n
From: |
Alberto Garcia |
Subject: |
[PATCH v11 33/34] qcow2: Assert that expand_zero_clusters_in_l1() does not support subclusters |
Date: |
Fri, 10 Jul 2020 18:13:15 +0200 |
This function is only used by qcow2_expand_zero_clusters() to
downgrade a qcow2 image to a previous version. This would require
transforming all extended L2 entries into normal L2 entries but this
is not a simple task and there are no plans to implement this at the
moment.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
---
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 bbf373ad21..81c49ba934 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -2159,6 +2159,9 @@ 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;
@@ -2227,7 +2230,8 @@ 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;
@@ -2298,6 +2302,8 @@ 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 10eb243164..23add2dfe3 100755
--- a/tests/qemu-iotests/061
+++ b/tests/qemu-iotests/061
@@ -303,6 +303,12 @@ $QEMU_IMG amend -o "compat=0.10" "$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 caa53e87cc..57d8c29f0b 100644
--- a/tests/qemu-iotests/061.out
+++ b/tests/qemu-iotests/061.out
@@ -532,6 +532,11 @@ Format specific information:
extended l2: 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 v11 14/34] qcow2: Add QCow2SubclusterType and qcow2_get_subcluster_type(), (continued)
- [PATCH v11 14/34] qcow2: Add QCow2SubclusterType and qcow2_get_subcluster_type(), Alberto Garcia, 2020/07/10
- [PATCH v11 17/34] qcow2: Add cluster type parameter to qcow2_get_host_offset(), Alberto Garcia, 2020/07/10
- [PATCH v11 28/34] qcow2: Add subcluster support to qcow2_co_pwrite_zeroes(), Alberto Garcia, 2020/07/10
- [PATCH v11 30/34] qcow2: Add prealloc field to QCowL2Meta, Alberto Garcia, 2020/07/10
- [PATCH v11 27/34] qcow2: Add subcluster support to handle_alloc_space(), Alberto Garcia, 2020/07/10
- [PATCH v11 29/34] qcow2: Add subcluster support to qcow2_measure(), Alberto Garcia, 2020/07/10
- [PATCH v11 34/34] iotests: Add tests for qcow2 images with extended L2 entries, Alberto Garcia, 2020/07/10
- [PATCH v11 23/34] qcow2: Add subcluster support to discard_in_l2_slice(), Alberto Garcia, 2020/07/10
- [PATCH v11 21/34] qcow2: Add subcluster support to qcow2_get_host_offset(), Alberto Garcia, 2020/07/10
- [PATCH v11 16/34] qcow2: Add qcow2_cluster_is_allocated(), Alberto Garcia, 2020/07/10
- [PATCH v11 33/34] qcow2: Assert that expand_zero_clusters_in_l1() does not support subclusters,
Alberto Garcia <=
- [PATCH v11 31/34] qcow2: Add the 'extended_l2' option and the QCOW2_INCOMPAT_EXTL2 bit, Alberto Garcia, 2020/07/10
- Re: [PATCH v11 00/34] Add subcluster allocation to qcow2, no-reply, 2020/07/10
- Re: [PATCH v11 00/34] Add subcluster allocation to qcow2, no-reply, 2020/07/10
- Re: [PATCH v11 00/34] Add subcluster allocation to qcow2, Max Reitz, 2020/07/14