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block: Catch backing files assigned to non-COW drivers

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Since we parse backing.* options to add a backing file from the command
line when the driver didn't assign one, it has been possible to have a
backing file for e.g. raw images (it just was never accessed).

This is obvious nonsense and should be rejected.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Kevin Wolf 2014-06-04 15:09:35 +02:00
parent 76c591b013
commit 8ee79e707a
9 changed files with 29 additions and 0 deletions
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7
block.c
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@ -1192,6 +1192,13 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
bdrv_get_full_backing_filename(bs, backing_filename, PATH_MAX);
}
if (!bs->drv || !bs->drv->supports_backing) {
ret = -EINVAL;
error_setg(errp, "Driver doesn't support backing files");
QDECREF(options);
goto free_exit;
}
backing_hd = bdrv_new("", errp);
if (bs->backing_format[0] != '\0') {

1
block/cow.c
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@ -414,6 +414,7 @@ static BlockDriver bdrv_cow = {
.bdrv_close = cow_close,
.bdrv_create = cow_create,
.bdrv_has_zero_init = bdrv_has_zero_init_1,
.supports_backing = true,
.bdrv_read = cow_co_read,
.bdrv_write = cow_co_write,

1
block/qcow.c
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@ -941,6 +941,7 @@ static BlockDriver bdrv_qcow = {
.bdrv_reopen_prepare = qcow_reopen_prepare,
.bdrv_create = qcow_create,
.bdrv_has_zero_init = bdrv_has_zero_init_1,
.supports_backing = true,
.bdrv_co_readv = qcow_co_readv,
.bdrv_co_writev = qcow_co_writev,

1
block/qcow2.c
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@ -2418,6 +2418,7 @@ static BlockDriver bdrv_qcow2 = {
.bdrv_save_vmstate = qcow2_save_vmstate,
.bdrv_load_vmstate = qcow2_load_vmstate,
.supports_backing = true,
.bdrv_change_backing_file = qcow2_change_backing_file,
.bdrv_refresh_limits = qcow2_refresh_limits,

1
block/qed.c
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@ -1652,6 +1652,7 @@ static BlockDriver bdrv_qed = {
.format_name = "qed",
.instance_size = sizeof(BDRVQEDState),
.create_opts = &qed_create_opts,
.supports_backing = true,
.bdrv_probe = bdrv_qed_probe,
.bdrv_rebind = bdrv_qed_rebind,

1
block/vmdk.c
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@ -2180,6 +2180,7 @@ static BlockDriver bdrv_vmdk = {
.bdrv_detach_aio_context = vmdk_detach_aio_context,
.bdrv_attach_aio_context = vmdk_attach_aio_context,
.supports_backing = true,
.create_opts = &vmdk_create_opts,
};

3
include/block/block_int.h
View File

@ -100,6 +100,9 @@ struct BlockDriver {
*/
bool bdrv_needs_filename;
/* Set if a driver can support backing files */
bool supports_backing;
/* For handling image reopen for split or non-split files */
int (*bdrv_reopen_prepare)(BDRVReopenState *reopen_state,
BlockReopenQueue *queue, Error **errp);

5
tests/qemu-iotests/051
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@ -100,6 +100,11 @@ echo
echo "info block" | run_qemu -drive file="$TEST_IMG",driver=qcow2,backing.file.filename="$TEST_IMG.orig" -nodefaults
# Drivers that don't support backing files
run_qemu -drive file="$TEST_IMG",driver=raw,backing.file.filename="$TEST_IMG.orig"
run_qemu -drive file="$TEST_IMG",file.backing.driver=file,file.backing.filename="$TEST_IMG.orig"
run_qemu -drive file="$TEST_IMG",file.backing.driver=qcow2,file.backing.file.filename="$TEST_IMG.orig"
echo
echo === Enable and disable lazy refcounting on the command line, plus some invalid values ===
echo

9
tests/qemu-iotests/051.out
View File

@ -53,6 +53,15 @@ ide0-hd0: TEST_DIR/t.qcow2 (qcow2)
Backing file: TEST_DIR/t.qcow2.orig (chain depth: 1)
(qemu) qququiquit
Testing: -drive file=TEST_DIR/t.qcow2,driver=raw,backing.file.filename=TEST_DIR/t.qcow2.orig
QEMU_PROG: -drive file=TEST_DIR/t.qcow2,driver=raw,backing.file.filename=TEST_DIR/t.qcow2.orig: could not open disk image TEST_DIR/t.qcow2: Driver doesn't support backing files
Testing: -drive file=TEST_DIR/t.qcow2,file.backing.driver=file,file.backing.filename=TEST_DIR/t.qcow2.orig
QEMU_PROG: -drive file=TEST_DIR/t.qcow2,file.backing.driver=file,file.backing.filename=TEST_DIR/t.qcow2.orig: could not open disk image TEST_DIR/t.qcow2: Driver doesn't support backing files
Testing: -drive file=TEST_DIR/t.qcow2,file.backing.driver=qcow2,file.backing.file.filename=TEST_DIR/t.qcow2.orig
QEMU_PROG: -drive file=TEST_DIR/t.qcow2,file.backing.driver=qcow2,file.backing.file.filename=TEST_DIR/t.qcow2.orig: could not open disk image TEST_DIR/t.qcow2: Driver doesn't support backing files
=== Enable and disable lazy refcounting on the command line, plus some invalid values ===