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| author | Eric Blake <eblake@redhat.com> | 2020-07-06 15:39:51 -0500 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2020-07-14 15:18:59 +0200 |
| commit | bc5ee6da7122f6fe93ed07241a44315a331487e9 (patch) | |
| tree | 93c3d374c430739c300d1413e50408b3baa51de5 /tests/qemu-iotests/082.out | |
| parent | add8200dd14041d059cc376eff91461fadd93ec5 (diff) | |
| download | qemu-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/qemu-iotests/082.out')
| -rw-r--r-- | tests/qemu-iotests/082.out | 2 |
1 files changed, 2 insertions, 0 deletions
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 |