[PATCH 1/2] qcow2: Prohibit backing file changes in 'qemu-img amend'
Eric Blake
eblake at redhat.com
Mon May 3 21:35:59 UTC 2021
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 at redhat.com>
---
docs/system/deprecated.rst | 12 ------------
docs/system/removed-features.rst | 12 ++++++++++++
block/qcow2.c | 13 ++++---------
tests/qemu-iotests/061 | 3 +++
tests/qemu-iotests/061.out | 3 ++-
tests/qemu-iotests/082.out | 6 ++++--
6 files changed, 25 insertions(+), 24 deletions(-)
diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst
index 80cae862528a..9ec1a9d0e03e 100644
--- a/docs/system/deprecated.rst
+++ b/docs/system/deprecated.rst
@@ -315,18 +315,6 @@ 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)
''''''''''''''''''''''''''''''''''''''''''''''''
diff --git a/docs/system/removed-features.rst b/docs/system/removed-features.rst
index 29e90601a51a..28b5df757d35 100644
--- a/docs/system/removed-features.rst
+++ b/docs/system/removed-features.rst
@@ -454,6 +454,18 @@ 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
-------------
diff --git a/block/qcow2.c b/block/qcow2.c
index 9727ae8fe341..898c4fc4464c 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -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;
}
}
diff --git a/tests/qemu-iotests/061 b/tests/qemu-iotests/061
index e26d94a0df31..9507c223bda4 100755
--- a/tests/qemu-iotests/061
+++ b/tests/qemu-iotests/061
@@ -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
diff --git a/tests/qemu-iotests/061.out b/tests/qemu-iotests/061.out
index ee30da266514..7ecbd4dea875 100644
--- a/tests/qemu-iotests/061.out
+++ b/tests/qemu-iotests/061.out
@@ -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.
diff --git a/tests/qemu-iotests/082.out b/tests/qemu-iotests/082.out
index b70c12c1393d..077ed0f2c7d9 100644
--- a/tests/qemu-iotests/082.out
+++ b/tests/qemu-iotests/082.out
@@ -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
--
2.31.1
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