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From: Alberto Garcia <berto@igalia.com>
To: qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
	Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
	Alberto Garcia <berto@igalia.com>,
	qemu-block@nongnu.org, Derek Su <dereksu@qnap.com>,
	Max Reitz <mreitz@redhat.com>
Subject: [PATCH v9 33/34] qcow2: Assert that expand_zero_clusters_in_l1() does not support subclusters
Date: Sun, 28 Jun 2020 13:02:42 +0200
Message-ID: <171529b6cfb1f6e109c7b27096e35e8aad628b87.1593342067.git.berto@igalia.com> (raw)
In-Reply-To: <cover.1593342067.git.berto@igalia.com>

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>
---
 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 c8217081f2..e8bb1f32f3 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -2157,6 +2157,9 @@ 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;
 
@@ -2225,7 +2228,8 @@ 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;
@@ -2296,6 +2300,8 @@ 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 f618259d47..a139d4f1fe 100644
--- a/tests/qemu-iotests/061.out
+++ b/tests/qemu-iotests/061.out
@@ -528,6 +528,11 @@ 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



  parent reply index

Thread overview: 71+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-28 11:02 [PATCH v9 00/34] Add subcluster allocation to qcow2 Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 01/34] qcow2: Make Qcow2AioTask store the full host offset Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 02/34] qcow2: Convert qcow2_get_cluster_offset() into qcow2_get_host_offset() Alberto Garcia
2020-06-30 10:19   ` Max Reitz
2020-06-30 10:27     ` Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 03/34] qcow2: Add calculate_l2_meta() Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 04/34] qcow2: Split cluster_needs_cow() out of count_cow_clusters() Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 05/34] qcow2: Process QCOW2_CLUSTER_ZERO_ALLOC clusters in handle_copied() Alberto Garcia
2020-06-30 10:38   ` Max Reitz
2020-06-28 11:02 ` [PATCH v9 06/34] qcow2: Add get_l2_entry() and set_l2_entry() Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 07/34] qcow2: Document the Extended L2 Entries feature Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 08/34] qcow2: Add dummy has_subclusters() function Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 09/34] qcow2: Add subcluster-related fields to BDRVQcow2State Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 10/34] qcow2: Add offset_to_sc_index() Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 11/34] qcow2: Add offset_into_subcluster() and size_to_subclusters() Alberto Garcia
2020-07-01 12:23   ` Max Reitz
2020-06-28 11:02 ` [PATCH v9 12/34] qcow2: Add l2_entry_size() Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 13/34] qcow2: Update get/set_l2_entry() and add get/set_l2_bitmap() Alberto Garcia
2020-07-01 12:28   ` Max Reitz
2020-06-28 11:02 ` [PATCH v9 14/34] qcow2: Add QCow2SubclusterType and qcow2_get_subcluster_type() Alberto Garcia
2020-07-01 12:52   ` Max Reitz
2020-07-01 16:26     ` Alberto Garcia
2020-07-02  9:57       ` Max Reitz
2020-07-02 22:00         ` Alberto Garcia
2020-07-03  7:17           ` Max Reitz
2020-06-28 11:02 ` [PATCH v9 15/34] qcow2: Add qcow2_get_subcluster_range_type() Alberto Garcia
2020-07-01 13:37   ` Max Reitz
2020-06-28 11:02 ` [PATCH v9 16/34] qcow2: Add qcow2_cluster_is_allocated() Alberto Garcia
2020-07-01 13:55   ` Max Reitz
2020-06-28 11:02 ` [PATCH v9 17/34] qcow2: Add cluster type parameter to qcow2_get_host_offset() Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 18/34] qcow2: Replace QCOW2_CLUSTER_* with QCOW2_SUBCLUSTER_* Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 19/34] qcow2: Handle QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 20/34] qcow2: Add subcluster support to calculate_l2_meta() Alberto Garcia
2020-07-02 11:30   ` Max Reitz
2020-06-28 11:02 ` [PATCH v9 21/34] qcow2: Add subcluster support to qcow2_get_host_offset() Alberto Garcia
2020-07-02 12:46   ` Max Reitz
2020-07-02 22:04     ` Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 22/34] qcow2: Add subcluster support to zero_in_l2_slice() Alberto Garcia
2020-07-02 12:56   ` Max Reitz
2020-06-28 11:02 ` [PATCH v9 23/34] qcow2: Add subcluster support to discard_in_l2_slice() Alberto Garcia
2020-07-02 13:24   ` Max Reitz
2020-06-28 11:02 ` [PATCH v9 24/34] qcow2: Add subcluster support to check_refcounts_l2() Alberto Garcia
2020-07-02 13:32   ` Max Reitz
2020-06-28 11:02 ` [PATCH v9 25/34] qcow2: Update L2 bitmap in qcow2_alloc_cluster_link_l2() Alberto Garcia
2020-07-02 14:01   ` Max Reitz
2020-06-28 11:02 ` [PATCH v9 26/34] qcow2: Clear the L2 bitmap when allocating a compressed cluster Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 27/34] qcow2: Add subcluster support to handle_alloc_space() Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 28/34] qcow2: Add subcluster support to qcow2_co_pwrite_zeroes() Alberto Garcia
2020-07-02 14:28   ` Max Reitz
2020-07-02 22:40     ` Alberto Garcia
2020-07-03  7:18       ` Max Reitz
2020-06-28 11:02 ` [PATCH v9 29/34] qcow2: Add subcluster support to qcow2_measure() Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 30/34] qcow2: Add prealloc field to QCowL2Meta Alberto Garcia
2020-07-02 14:50   ` Max Reitz
2020-07-02 14:58     ` Eric Blake
2020-07-02 15:09       ` Max Reitz
2020-07-02 23:05         ` Alberto Garcia
2020-07-03  7:22           ` Max Reitz
2020-06-28 11:02 ` [PATCH v9 31/34] qcow2: Add the 'extended_l2' option and the QCOW2_INCOMPAT_EXTL2 bit Alberto Garcia
2020-07-02 15:13   ` Max Reitz
2020-07-03 12:43     ` Alberto Garcia
2020-06-28 11:02 ` [PATCH v9 32/34] qcow2: Allow preallocation and backing files if extended_l2 is set Alberto Garcia
2020-07-03  7:45   ` Max Reitz
2020-06-28 11:02 ` Alberto Garcia [this message]
2020-07-03  7:46   ` [PATCH v9 33/34] qcow2: Assert that expand_zero_clusters_in_l1() does not support subclusters Max Reitz
2020-06-28 11:02 ` [PATCH v9 34/34] iotests: Add tests for qcow2 images with extended L2 entries Alberto Garcia
2020-07-03  9:49   ` Max Reitz
2020-07-03 13:06     ` Alberto Garcia
2020-07-03 13:47       ` Max Reitz
2020-07-03 15:20         ` Alberto Garcia
2020-07-06 13:57       ` Eric Blake

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