diff options
| author | Alberto Garcia <berto@igalia.com> | 2020-03-31 13:43:45 +0200 |
|---|---|---|
| committer | Max Reitz <mreitz@redhat.com> | 2020-04-07 13:51:09 +0200 |
| commit | 80f5c01183597b075157eb7bedbcb8691f8fa1d1 (patch) | |
| tree | e1716cf4029012456fe1a8acb64de45302e26a12 /tests/qemu-iotests/290.out | |
| parent | 53ef8a92eb04ee19640f5aad3bff36cd4a36c250 (diff) | |
qcow2: Forbid discard in qcow2 v2 images with backing files
A discard request deallocates the selected clusters so they read back
as zeroes. This is done by clearing the cluster offset field and
setting QCOW_OFLAG_ZERO in the L2 entry.
This flag is however only supported when qcow_version >= 3. In older
images the cluster is simply deallocated, exposing any possible stale
data from the backing file.
Since discard is an advisory operation it's safer to simply forbid it
in this scenario.
Note that we are adding this check to qcow2_co_pdiscard() and not to
qcow2_cluster_discard() or discard_in_l2_slice() because the last
two are also used by qcow2_snapshot_create() to discard the clusters
used by the VM state. In this case there's no risk of exposing stale
data to the guest and we really want that the clusters are always
discarded.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-Id: <20200331114345.29993-1-berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'tests/qemu-iotests/290.out')
| -rw-r--r-- | tests/qemu-iotests/290.out | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/tests/qemu-iotests/290.out b/tests/qemu-iotests/290.out new file mode 100644 index 0000000000..d2259c823b --- /dev/null +++ b/tests/qemu-iotests/290.out @@ -0,0 +1,61 @@ +QA output created by 290 + +### Test 'qemu-io -c discard' on a QCOW2 image without a backing file + +# Create an image with compat=0.10 without a backing file +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=131072 +# Fill all clusters with data and then discard them +wrote 131072/131072 bytes at offset 0 +128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +discard 131072/131072 bytes at offset 0 +128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +# Read the data from the discarded clusters +read 131072/131072 bytes at offset 0 +128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +# Output of qemu-img map +Offset Length Mapped to File +# Create an image with compat=1.1 without a backing file +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=131072 +# Fill all clusters with data and then discard them +wrote 131072/131072 bytes at offset 0 +128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +discard 131072/131072 bytes at offset 0 +128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +# Read the data from the discarded clusters +read 131072/131072 bytes at offset 0 +128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +# Output of qemu-img map +Offset Length Mapped to File + +### Test 'qemu-io -c discard' on a QCOW2 image with a backing file + +# Create a backing image and fill it with data +Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=131072 +wrote 131072/131072 bytes at offset 0 +128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +# Create an image with compat=0.10 and a backing file +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=131072 backing_file=TEST_DIR/t.IMGFMT.base +# Fill all clusters with data and then discard them +wrote 131072/131072 bytes at offset 0 +128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +discard 131072/131072 bytes at offset 0 +128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +# Read the data from the discarded clusters +read 131072/131072 bytes at offset 0 +128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +# Output of qemu-img map +Offset Length Mapped to File +0 0x20000 0x50000 TEST_DIR/t.qcow2 +# Create an image with compat=1.1 and a backing file +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=131072 backing_file=TEST_DIR/t.IMGFMT.base +# Fill all clusters with data and then discard them +wrote 131072/131072 bytes at offset 0 +128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +discard 131072/131072 bytes at offset 0 +128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +# Read the data from the discarded clusters +read 131072/131072 bytes at offset 0 +128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +# Output of qemu-img map +Offset Length Mapped to File +*** done |