Kevin Wolf d29d3d1f80 block: Relax restrictions for blockdev-snapshot ... blockdev-snapshot returned an error if the overlay was already in use, which it defined as having any BlockBackend parent. This is in fact both too strict (some parents can tolerate the change of visible data caused by attaching a backing file) and too loose (some non-BlockBackend parents may not be happy with it). One important use case that is prevented by the too strict check is live storage migration with blockdev-mirror. Here, the target node is usually opened without a backing file so that the active layer is mirrored while its backing chain can be copied in the background. The backing chain should be attached to the mirror target node when finalising the job, just before switching the users of the source node to the new copy (at which point the mirror job still has a reference to the node). drive-mirror did this automatically, but with blockdev-mirror this is the job of the QMP client, so it needs a way to do this. blockdev-snapshot is the obvious way, so this patch makes it work in this scenario. The new condition is that no parent uses CONSISTENT_READ permissions. This will ensure that the operation will still be blocked when the node is attached to the guest device, so blockdev-snapshot remains safe. (For the sake of completeness, x-blockdev-reopen can be used to achieve the same, however it is a big hammer, performs the graph change completely unchecked and is still experimental. So even with the option of using x-blockdev-reopen, there are reasons why blockdev-snapshot should be able to perform this operation.) Signed-off-by: Kevin Wolf <kwolf@redhat.com> Message-Id: <20200310113831.27293-3-kwolf@redhat.com> Reviewed-by: Peter Krempa <pkrempa@redhat.com> Tested-by: Peter Krempa <pkrempa@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>		2020-03-11 15:54:38 +01:00
..
acceptance	tests/acceptance/integratorcp: Verify Tux is displayed on framebuffer	2020-02-28 16:14:57 +00:00
data	rebuild-expected-aml.sh: remind about the process	2020-02-25 08:23:18 -05:00
decode	decodetree: Allow !function with no input bits	2019-08-19 08:03:41 -07:00
docker	configure: Enable test and libs for zstd	2020-02-28 09:24:43 +01:00
fp	testing: don't nest build for fp-test	2020-01-09 11:41:29 +00:00
guest-debug	drop "from __future__ import print_function"	2020-02-07 15:15:16 +01:00
image-fuzzer	image-fuzzer: Use OSerror.strerror instead of tuple subscript	2019-11-05 16:36:11 +01:00
keys
migration	drop "from __future__ import print_function"	2020-02-07 15:15:16 +01:00
multiboot	tests/multiboot: Fix load address of test kernels	2019-07-30 12:25:43 +02:00
perf/block/qcow2	tests/perf: Test lseek influence on qcow2 block-status	2019-06-04 15:20:41 +02:00
plugin	tests/plugins: make howvec clean-up after itself.	2020-02-25 20:20:23 +00:00
qapi-schema	qapi: Drop conditionals for Python 2	2020-03-05 09:24:11 +01:00
qemu-iotests	block: Relax restrictions for blockdev-snapshot	2020-03-11 15:54:38 +01:00
qtest	qtest: fix fuzzer-related 80-char limit violations	2020-03-06 10:33:26 +00:00
rocker
tcg	tests/tcg/aarch64: Add newline in pauth-1 printf	2020-03-05 16:09:19 +00:00
uefi-test-tools	edk2 build scripts: work around TianoCore#1607 without forcing Python 2	2019-10-07 15:14:15 +02:00
vm	configure: detect and report genisoimage	2020-03-04 09:57:33 +00:00
vmstate-static-checker-data
.gitignore	qapi: Generate command registration stuff into separate files	2020-01-14 11:01:58 +01:00
atomic64-bench.c
atomic_add-bench.c
benchmark-crypto-cipher.c	tests: benchmark crypto with fixed data size, not time period	2019-10-28 13:32:21 +01:00
benchmark-crypto-hash.c	tests: benchmark crypto with fixed data size, not time period	2019-10-28 13:32:21 +01:00
benchmark-crypto-hmac.c
check-block-qdict.c
check-block.sh	build: move TARGET_GPROF to config-host.mak	2020-02-12 16:29:27 +01:00
check-qdict.c	tests: Move qdict-test-data.txt to tests/data/qobject/	2019-03-07 22:05:54 +01:00
check-qjson.c	test: Use g_strndup instead of plain strndup	2019-08-21 10:27:13 +02:00
check-qlist.c
check-qlit.c
check-qnull.c
check-qnum.c
check-qobject.c
check-qom-interface.c
check-qom-proplist.c
check-qstring.c
crypto-tls-psk-helpers.c
crypto-tls-psk-helpers.h	Supply missing header guards	2019-06-12 13:20:21 +02:00
crypto-tls-x509-helpers.c
crypto-tls-x509-helpers.h	Supply missing header guards	2019-06-12 13:20:21 +02:00
dbus-vmstate-daemon.sh	tests: add dbus-vmstate-test	2020-01-06 18:41:32 +04:00
io-channel-helpers.c
io-channel-helpers.h	Normalize position of header guard	2019-06-12 13:20:20 +02:00
iothread.c	tests/iothread: Always connect iothread GSource to a GMainContext	2020-01-07 14:32:57 +00:00
iothread.h
Makefile.include	rcu_queue: add QSLIST functions	2020-02-22 08:26:47 +00:00
pkix_asn1_tab.c
ptimer-test-stubs.c	util/qemu-timer: refactor deadline calculation for external timers	2019-08-20 17:26:21 +02:00
ptimer-test.c	tests/ptimer: Remove unnecessary inclusion of libqtest.h	2020-01-12 11:42:40 +01:00
ptimer-test.h
qht-bench.c
rcutorture.c	tests/rcutorture: mild documenting refactor of update thread	2020-02-25 17:42:59 +00:00
requirements.txt	tests/acceptance: bump avocado requirements to 76.0	2020-03-04 09:57:33 +00:00
socket-helpers.c	tests: specify the address family when checking bind	2019-08-22 17:30:25 +04:00
socket-helpers.h	tests: specify the address family when checking bind	2019-08-22 17:30:25 +04:00
test-aio-multithread.c	tests: Do not use "\n" in g_test_message() strings	2019-03-07 22:16:22 +01:00
test-aio.c	util/async: make bh_aio_poll() O(1)	2020-02-22 08:26:47 +00:00
test-authz-list.c	Include qemu/module.h where needed, drop it from qemu-common.h	2019-06-12 13:18:33 +02:00
test-authz-listfile.c	Include qemu/module.h where needed, drop it from qemu-common.h	2019-06-12 13:18:33 +02:00
test-authz-pam.c	Include qemu/module.h where needed, drop it from qemu-common.h	2019-06-12 13:18:33 +02:00
test-authz-simple.c	Include qemu/module.h where needed, drop it from qemu-common.h	2019-06-12 13:18:33 +02:00
test-base64.c
test-bdrv-drain.c	job: drop job_drain	2019-09-10 08:58:43 +02:00
test-bdrv-graph-mod.c	Include qemu/main-loop.h less	2019-08-16 13:31:52 +02:00
test-bitcnt.c
test-bitmap.c	tests: use g_test_rand_int	2019-12-17 09:05:23 +01:00
test-bitops.c
test-block-backend.c	Include qemu/main-loop.h less	2019-08-16 13:31:52 +02:00
test-block-iothread.c	block: Add @exact parameter to bdrv_co_truncate()	2019-10-28 12:00:07 +01:00
test-blockjob-txn.c	job: drop job_drain	2019-09-10 08:58:43 +02:00
test-blockjob.c	tests-blockjob: Use error_free_or_abort()	2019-12-18 08:36:16 +01:00
test-bufferiszero.c
test-char.c	chardev: Use QEMUChrEvent enum in IOEventHandler typedef	2020-01-08 11:15:35 +01:00
test-clone-visitor.c	tests: Rename UserDefNativeListUnion to UserDefListUnion	2019-03-05 14:43:11 +01:00
test-coroutine.c	tests: Do not use "\n" in g_test_message() strings	2019-03-07 22:16:22 +01:00
test-crypto-afsplit.c
test-crypto-block.c	Include qemu/module.h where needed, drop it from qemu-common.h	2019-06-12 13:18:33 +02:00
test-crypto-cipher.c
test-crypto-hash.c
test-crypto-hmac.c
test-crypto-ivgen.c
test-crypto-pbkdf.c
test-crypto-secret.c
test-crypto-tlscredsx509.c	glib: use portable g_setenv()	2019-12-17 09:05:23 +01:00
test-crypto-tlssession.c	glib: use portable g_setenv()	2019-12-17 09:05:23 +01:00
test-crypto-xts.c
test-cutils.c
test-hbitmap.c	util/hbitmap: strict hbitmap_reset	2019-10-17 17:02:32 -04:00
test-image-locking.c	Include qemu/main-loop.h less	2019-08-16 13:31:52 +02:00
test-int128.c
test-io-channel-buffer.c	Include qemu/module.h where needed, drop it from qemu-common.h	2019-06-12 13:18:33 +02:00
test-io-channel-command.c	Include qemu/module.h where needed, drop it from qemu-common.h	2019-06-12 13:18:33 +02:00
test-io-channel-file.c	Include qemu/module.h where needed, drop it from qemu-common.h	2019-06-12 13:18:33 +02:00
test-io-channel-socket.c	socket: Add num connections to qio_channel_socket_async()	2019-09-03 23:24:42 +02:00
test-io-channel-tls.c	glib: use portable g_setenv()	2019-12-17 09:05:23 +01:00
test-io-task.c	Include qemu/module.h where needed, drop it from qemu-common.h	2019-06-12 13:18:33 +02:00
test-iov.c
test-keyval.c	test-keyval: Tighten test of trailing crap after size	2019-12-18 12:28:44 +01:00
test-logging.c	test-logging: Fix -Werror=maybe-uninitialized warning	2020-02-04 09:00:57 +01:00
test-mul64.c
test-opts-visitor.c
test-qapi-util.c
test-qdev-global-props.c	qdev: set properties with device_class_set_props()	2020-01-24 20:59:15 +01:00
test-qdist.c
test-qemu-opts.c
test-qga.c	tests: use g_test_rand_int	2019-12-17 09:05:23 +01:00
test-qgraph.c	tests: test-qgraph: fix a memory leak	2019-03-11 16:33:49 +01:00
test-qht-par.c
test-qht.c
test-qmp-cmds.c	qapi: Generate command registration stuff into separate files	2020-01-14 11:01:58 +01:00
test-qmp-event.c
test-qobject-input-visitor.c	tests: Rename UserDefNativeListUnion to UserDefListUnion	2019-03-05 14:43:11 +01:00
test-qobject-output-visitor.c	tests: Clean up initialization of Error *err variables	2019-12-18 08:36:15 +01:00
test-rcu-list.c	tests: Fix a bug with count variables	2020-03-06 10:35:15 +00:00
test-rcu-simpleq.c
test-rcu-slist.c	rcu_queue: add QSLIST functions	2020-02-22 08:26:47 +00:00
test-rcu-tailq.c
test-replication.c	tests/test-replication.c: Add test for for secondary node continuing replication	2020-03-03 18:04:47 +08:00
test-shift128.c
test-string-input-visitor.c	tests: Fix uninitialized byte in test_visitor_in_fuzz	2019-08-20 17:26:19 +02:00
test-string-output-visitor.c	tests: Clean up initialization of Error *err variables	2019-12-18 08:36:15 +01:00
test-thread-pool.c	test-thread-pool: be more reliable	2019-06-03 14:03:00 +02:00
test-throttle.c	test-throttle: Fix uninitialized use of burst_length	2019-08-20 17:26:19 +02:00
test-timed-average.c
test-util-filemonitor.c	tests/test-util-filemonitor: Skip test on non-x86 Travis containers	2019-12-18 20:17:45 +00:00
test-util-sockets.c	hmp: Fail gracefully if chardev is already in use	2020-03-06 17:21:28 +01:00
test-uuid.c
test-visitor-serialization.c
test-vmstate.c	test-vmstate: Fix memleaks in test_load_qlist	2020-02-28 09:25:49 +01:00
test-write-threshold.c
test-x86-cpuid.c	i386: Update new x86_apicid parsing rules with die_offset support	2019-07-05 17:08:03 -03:00
test-xbzrle.c
vhost-user-bridge.c	core: replace getpagesize() with qemu_real_host_page_size	2019-10-26 15:38:06 +02:00