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qcow2: Prohibit backing file changes in 'qemu-img amend'

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This was deprecated back in bc5ee6da7 (qcow2: Deprecate use of
qemu-img amend to change backing file), and no one in the meantime has
given any reasons why it should be supported.  Time to make change
attempts a hard error (but for convenience, specifying the _same_
backing chain is not forbidden).  Update a couple of iotests to match.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210503213600.569128-2-eblake@redhat.com>
Reviewed-by: Connor Kuehl <ckuehl@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Eric Blake 2021-05-03 14:35:59 -07:00 committed by Kevin Wolf
parent 2842ff2d81
commit 5a385bf5c5
6 changed files with 25 additions and 24 deletions
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13
block/qcow2.c
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@ -5620,15 +5620,10 @@ static int qcow2_amend_options(BlockDriverState *bs, QemuOpts *opts,
if (backing_file || backing_format) {
if (g_strcmp0(backing_file, s->image_backing_file) ||
g_strcmp0(backing_format, s->image_backing_format)) {
warn_report("Deprecated use of amend to alter the backing file; "
"use qemu-img rebase instead");
}
ret = qcow2_change_backing_file(bs,
backing_file ?: s->image_backing_file,
backing_format ?: s->image_backing_format);
if (ret < 0) {
error_setg_errno(errp, -ret, "Failed to change the backing file");
return ret;
error_setg(errp, "Cannot amend the backing file");
error_append_hint(errp,
"You can use 'qemu-img rebase' instead.\n");
return -EINVAL;
}
}

12
docs/system/deprecated.rst
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@ -282,18 +282,6 @@ this CPU is also deprecated.
Related binaries
----------------
qemu-img amend to adjust backing file (since 5.1)
'''''''''''''''''''''''''''''''''''''''''''''''''
The use of ``qemu-img amend`` to modify the name or format of a qcow2
backing image is deprecated; this functionality was never fully
documented or tested, and interferes with other amend operations that
need access to the original backing image (such as deciding whether a
v3 zero cluster may be left unallocated when converting to a v2
image). Rather, any changes to the backing chain should be performed
with ``qemu-img rebase -u`` either before or after the remaining
changes being performed by amend, as appropriate.
qemu-img backing file without format (since 5.1)
''''''''''''''''''''''''''''''''''''''''''''''''

12
docs/system/removed-features.rst
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@ -491,6 +491,18 @@ topologies described with -smp include all possible cpus, i.e.
The ``enforce-config-section`` property was replaced by the
``-global migration.send-configuration={on|off}`` option.
qemu-img amend to adjust backing file (removed in 6.1)
''''''''''''''''''''''''''''''''''''''''''''''''''''''
The use of ``qemu-img amend`` to modify the name or format of a qcow2
backing image was never fully documented or tested, and interferes
with other amend operations that need access to the original backing
image (such as deciding whether a v3 zero cluster may be left
unallocated when converting to a v2 image). Any changes to the
backing chain should be performed with ``qemu-img rebase -u`` either
before or after the remaining changes being performed by amend, as
appropriate.
Block devices
-------------

3
tests/qemu-iotests/061
View File

@ -167,6 +167,9 @@ _make_test_img -o "compat=1.1" 64M
TEST_IMG="$TEST_IMG.base" _make_test_img -o "compat=1.1" 64M
$QEMU_IO -c "write -P 0x2a 0 128k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "read -P 0 0 128k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG amend -o "backing_file=$TEST_IMG.base,backing_fmt=qcow2" \
"$TEST_IMG" && echo "unexpected pass"
$QEMU_IMG rebase -u -b "$TEST_IMG.base" -F qcow2 "$TEST_IMG"
$QEMU_IMG amend -o "backing_file=$TEST_IMG.base,backing_fmt=qcow2" "$TEST_IMG"
$QEMU_IO -c "read -P 0x2a 0 128k" "$TEST_IMG" | _filter_qemu_io
_check_test_img

3
tests/qemu-iotests/061.out
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@ -370,7 +370,8 @@ 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
qemu-img: Cannot amend the backing file
You can 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.

6
tests/qemu-iotests/082.out
View File

@ -808,12 +808,14 @@ 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
qemu-img: Cannot amend the backing file
You can 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
qemu-img: Cannot amend the backing file
You can use 'qemu-img rebase' instead.
Testing: rebase -u -b -f qcow2 TEST_DIR/t.qcow2