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authorEric Blake <eblake@redhat.com>2020-07-06 15:39:51 -0500
committerKevin Wolf <kwolf@redhat.com>2020-07-14 15:18:59 +0200
commitbc5ee6da7122f6fe93ed07241a44315a331487e9 (patch)
tree93c3d374c430739c300d1413e50408b3baa51de5 /tests
parentadd8200dd14041d059cc376eff91461fadd93ec5 (diff)
downloadqemu-bc5ee6da7122f6fe93ed07241a44315a331487e9.zip
qcow2: Deprecate use of qemu-img amend to change backing file
The use of 'qemu-img amend' to change qcow2 backing files is not tested very well. In particular, our implementation has a bug where if a new backing file is provided without a format, then the prior format is blindly reused, even if this results in data corruption, but this is not caught by iotests. There are also situations where amending other options needs access to the original backing file (for example, on a downgrade to a v2 image, knowing whether a v3 zero cluster must be allocated or may be left unallocated depends on knowing whether the backing file already reads as zero), but the command line does not have a nice way to tell us both the backing file to use for opening the image as well as the backing file to install after the operation is complete. Even if we do allow changing the backing file, it is redundant with the existing ability to change backing files via 'qemu-img rebase -u'. It is time to deprecate this support (leaving the existing behavior intact, even if it is buggy), and at a point in the future, require the use of only 'qemu-img rebase' for adjusting backing chain relations, saving 'qemu-img amend' for changes unrelated to the backing chain. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20200706203954.341758-8-eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'tests')
-rw-r--r--tests/qemu-iotests/061.out1
-rw-r--r--tests/qemu-iotests/082.out2
2 files changed, 3 insertions, 0 deletions
diff --git a/tests/qemu-iotests/061.out b/tests/qemu-iotests/061.out
index b0f8befe30..44e3c624f9 100644
--- a/tests/qemu-iotests/061.out
+++ b/tests/qemu-iotests/061.out
@@ -370,6 +370,7 @@ wrote 131072/131072 bytes at offset 0
128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
read 131072/131072 bytes at offset 0
128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-img: warning: Deprecated use of amend to alter the backing file; use qemu-img rebase instead
read 131072/131072 bytes at offset 0
128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
No errors were found on the image.
diff --git a/tests/qemu-iotests/082.out b/tests/qemu-iotests/082.out
index f7b3d54b28..a38a26fc57 100644
--- a/tests/qemu-iotests/082.out
+++ b/tests/qemu-iotests/082.out
@@ -783,10 +783,12 @@ Amend options for 'qcow2':
size=<size> - Virtual disk size
Testing: amend -f qcow2 -o backing_file=TEST_DIR/t.qcow2,,help TEST_DIR/t.qcow2
+qemu-img: warning: Deprecated use of amend to alter the backing file; use qemu-img rebase instead
Testing: rebase -u -b -f qcow2 TEST_DIR/t.qcow2
Testing: amend -f qcow2 -o backing_file=TEST_DIR/t.qcow2,,? TEST_DIR/t.qcow2
+qemu-img: warning: Deprecated use of amend to alter the backing file; use qemu-img rebase instead
Testing: rebase -u -b -f qcow2 TEST_DIR/t.qcow2