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block: BDRV_O_NO_IO for backing file on creation

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When creating an image file with a backing file, we generally try to
open the backing file (unless -u was specified), mostly to verify that
it is there, but also to get the file size if none was specified for the
new image.

For neither of these things do we need data I/O, and so we can pass
BDRV_O_NO_IO when opening the backing file.  This allows us to open even
encrypted backing images without requiring the user to provide a secret.

This makes the -u switch in iotests 189 and 198 unnecessary (and the
$size parameter), so drop it, because this way we get regression tests
for this patch here.

Fixes: https://gitlab.com/qemu-project/qemu/-/issues/441
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210622140030.212487-1-mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Max Reitz 2021-06-22 16:00:30 +02:00 committed by Kevin Wolf
parent 97efa8698e
commit d5b2399458
3 changed files with 7 additions and 3 deletions
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6
block.c
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@ -6553,9 +6553,13 @@ void bdrv_img_create(const char *filename, const char *fmt,
} }
assert(full_backing); assert(full_backing);
/* backing files always opened read-only */ /*
* No need to do I/O here, which allows us to open encrypted
* backing images without needing the secret
*/
back_flags = flags; back_flags = flags;
back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING); back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
back_flags |= BDRV_O_NO_IO;
backing_options = qdict_new(); backing_options = qdict_new();
if (backing_fmt) { if (backing_fmt) {

2
tests/qemu-iotests/189
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@ -67,7 +67,7 @@ echo "== verify pattern =="
$QEMU_IO --object $SECRET0 -c "read -P 0xa 0 $size" --image-opts $IMGSPECBASE | _filter_qemu_io | _filter_testdir $QEMU_IO --object $SECRET0 -c "read -P 0xa 0 $size" --image-opts $IMGSPECBASE | _filter_qemu_io | _filter_testdir
echo "== create overlay ==" echo "== create overlay =="
_make_test_img --object $SECRET1 -o "encrypt.format=luks,encrypt.key-secret=sec1,encrypt.iter-time=10" -u -b "$TEST_IMG_BASE" -F $IMGFMT $size _make_test_img --object $SECRET1 -o "encrypt.format=luks,encrypt.key-secret=sec1,encrypt.iter-time=10" -b "$TEST_IMG_BASE" -F $IMGFMT
echo echo
echo "== writing part of a cluster ==" echo "== writing part of a cluster =="

2
tests/qemu-iotests/198
View File

@ -64,7 +64,7 @@ echo "== writing whole image base =="
$QEMU_IO --object $SECRET0 -c "write -P 0xa 0 $size" --image-opts $IMGSPECBASE | _filter_qemu_io | _filter_testdir $QEMU_IO --object $SECRET0 -c "write -P 0xa 0 $size" --image-opts $IMGSPECBASE | _filter_qemu_io | _filter_testdir
echo "== create overlay ==" echo "== create overlay =="
_make_test_img --object $SECRET1 -o "encrypt.format=luks,encrypt.key-secret=sec1,encrypt.iter-time=10" -u -b "$TEST_IMG_BASE" -F $IMGFMT $size _make_test_img --object $SECRET1 -o "encrypt.format=luks,encrypt.key-secret=sec1,encrypt.iter-time=10" -b "$TEST_IMG_BASE" -F $IMGFMT
echo echo
echo "== writing whole image layer ==" echo "== writing whole image layer =="