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| 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/046.out | |
| parent | 53ef8a92eb04ee19640f5aad3bff36cd4a36c250 (diff) | |
| download | qemu-80f5c01183597b075157eb7bedbcb8691f8fa1d1.zip qemu-80f5c01183597b075157eb7bedbcb8691f8fa1d1.tar.gz qemu-80f5c01183597b075157eb7bedbcb8691f8fa1d1.tar.bz2 | |
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/046.out')
| -rw-r--r-- | tests/qemu-iotests/046.out | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/tests/qemu-iotests/046.out b/tests/qemu-iotests/046.out index ca2c740..7078304 100644 --- a/tests/qemu-iotests/046.out +++ b/tests/qemu-iotests/046.out @@ -187,8 +187,10 @@ read 24576/24576 bytes at offset 491520 24 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) read 8192/8192 bytes at offset 516096 8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) -read 24576/24576 bytes at offset 524288 -24 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +read 4096/4096 bytes at offset 524288 +4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +read 20480/20480 bytes at offset 528384 +20 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) read 8192/8192 bytes at offset 548864 8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) read 8192/8192 bytes at offset 557056 @@ -199,8 +201,10 @@ read 24576/24576 bytes at offset 622592 24 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) read 8192/8192 bytes at offset 647168 8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) -read 24576/24576 bytes at offset 655360 -24 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +read 4096/4096 bytes at offset 655360 +4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +read 20480/20480 bytes at offset 659456 +20 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) read 8192/8192 bytes at offset 679936 8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) read 8192/8192 bytes at offset 688128 |