Python:
* introduce "python" directory with module namespace
* log QEMU launch command line on qemu.QEMUMachine
Acceptance Tests:
* initrd 4GiB+ test
* migration test
* multi vm support in test class
* bump Avocado version and drop "🥑 enable"
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Merge remote-tracking branch 'remotes/cleber/tags/python-next-pull-request' into staging
Python queue, 2019-02-22
Python:
* introduce "python" directory with module namespace
* log QEMU launch command line on qemu.QEMUMachine
Acceptance Tests:
* initrd 4GiB+ test
* migration test
* multi vm support in test class
* bump Avocado version and drop "🥑 enable"
# gpg: Signature made Fri 22 Feb 2019 19:37:07 GMT
# gpg: using RSA key 657E8D33A5F209F3
# gpg: Good signature from "Cleber Rosa <crosa@redhat.com>" [marginal]
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg: It is not certain that the signature belongs to the owner.
# Primary key fingerprint: 7ABB 96EB 8B46 B94D 5E0F E9BB 657E 8D33 A5F2 09F3
* remotes/cleber/tags/python-next-pull-request:
Acceptance tests: expect boot to extract 2GiB+ initrd with linux-v4.16
Acceptance tests: use linux-3.6 and set vm memory to 4GiB
tests.acceptance: adds simple migration test
tests.acceptance: adds multi vm capability for acceptance tests
scripts/qemu.py: log QEMU launch command line
Introduce a Python module structure
Acceptance tests: drop usage of "🥑 enable"
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
When we run "certtool 2>&1 | head -1" the latter command is likely to
complete and exit before certtool has written everything it wants to
stderr. In at least the RHEL-7 gnutls 3.3.29 this causes certtool to
quit with broken pipe before it has finished writing the desired
output file to disk. This causes non-deterministic failures of the
iotest 233 because the certs are sometimes zero length files.
If certtool fails the "head -1" means we also lose any useful error
message it would have printed.
Thus this patch gets rid of the pipe and post-processes the output in a
more flexible & reliable manner.
Reported-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20190220145819.30969-3-berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
If we abort the iotest early the server.log file might contain useful
information for diagnosing the problem. Ensure its contents are
displayed in this case.
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20190220145819.30969-2-berrange@redhat.com>
[eblake: fix shell quoting]
Signed-off-by: Eric Blake <eblake@redhat.com>
The data type for bytes in Python 3 differs from the one in Python 2.
The type cast that is compatible with both versions was applied.
Signed-off-by: Nir Soffer <nsoffer@redhat.com>
Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reported-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <1551197495-24425-1-git-send-email-andrey.shinkevich@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
VDI keeps the whole bitmap in memory, and the maximum size (which is
tested here) is 2 GB. This may not be available on all machines, and it
rarely is available when running a 32 bit build.
Fix this by making VM.run_job() return the error string if an error
occurred, and checking whether that contains "Could not allocate bmap"
in 211. If so, the test is skipped.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190218180646.30282-1-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
The previous patch includes the LUKS payload overhead into the qemu-img
measure calculation for qcow2. Update qemu-iotests 178 to exercise this
new code path.
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20190218104525.23674-3-stefanha@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This follows what qmp() does, so the output will correspond to the
actual QMP command.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190210145736.1486-11-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Adding a telnet monitor for no real purpose on a fixed port is not so
great. Just use a null monitor instead.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20190210145736.1486-10-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
8908b253c4 has implemented filtering of
remote paths for NFS, but forgot SSH. This patch takes care of that.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20190210145736.1486-9-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
filter_qmp_testfiles() currently filters the filename only for specific
keys. However, there are more keys that take filenames (such as
block-commit's @top and @base, or ssh's @path), and it does not make
sense to list them all here. "$TEST_DIR/$PID-" should have enough
entropy not to appear anywhere randomly.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20190210145736.1486-8-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
On Python 2.x, strings are not always unicode strings. This function
checks whether a given value is a plain string, or a unicode string (if
there is a difference).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20190210145736.1486-7-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
With IMGOPTSSYNTAX, $TEST_IMG is useless for this test (it only tests
the file-posix protocol driver). Therefore, if $TEST_IMG_FILE is set,
use that instead.
Because this test requires the file protocol, $TEST_IMG_FILE will always
be set if $IMGOPTSSYNTAX is true.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20190210145736.1486-5-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This test creates no such file.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20190210145736.1486-4-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
math.ceil() returns an integer on Python 3.x, but a float on Python 2.x.
range() always needs integers, so we need an explicit conversion on 2.x
(which does not hurt on 3.x).
It is not quite clear whether we want to support Python 2.x for any
prolonged time, but this may as well be fixed along with the other
issues some iotests have right now.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20190210145736.1486-3-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
A previous commit removed the default filters for qmp_log with the
intention to make them explicit; but this happened only for test 206.
There are more tests (for more exotic image formats than qcow2) which
require the filename filter, though.
Note that 237 is still broken for Python 2.x, which is fixed in the next
commit.
Fixes: f8ca8609d8
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20190210145736.1486-2-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Currently, BlockDriver.bdrv_refresh_filename() is supposed to both
refresh the filename (BDS.exact_filename) and set BDS.full_open_options.
Now that we have generic code in the central bdrv_refresh_filename() for
creating BDS.full_open_options, we can drop the latter part from all
BlockDriver.bdrv_refresh_filename() implementations.
This also means that we can drop all of the existing default code for
this from the global bdrv_refresh_filename() itself.
Furthermore, we now have to call BlockDriver.bdrv_refresh_filename()
after having set BDS.full_open_options, because the block driver's
implementation should now be allowed to depend on BDS.full_open_options
being set correctly.
Finally, with this patch we can drop the @options parameter from
BlockDriver.bdrv_refresh_filename(); also, add a comment on this
function's purpose in block/block_int.h while touching its interface.
This completely obsoletes blklogwrite's implementation of
.bdrv_refresh_filename().
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190201192935.18394-25-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Instead of having every block driver which implements
bdrv_refresh_filename() copy all of the strong runtime options over to
bs->full_open_options, implement this process generically in
bdrv_refresh_filename().
This patch only adds this new generic implementation, it does not remove
the old functionality. This is done in a follow-up patch.
With this patch, some superfluous information (that should never have
been there) may be removed from some JSON filenames, as can be seen in
the change to iotests 110's and 228's reference outputs.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190201192935.18394-24-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Test 110 tests relative backing filenames for complex BDS trees. Now
that the originally supposedly failing test passes, let us add a new
failing test: Quorum can never work automatically (without detecting
whether all child nodes have the same base directory, but that would be
rather inconsistent behavior).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-21-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
bdrv_get_full_backing_filename_from_filename() breaks down when it comes
to JSON filenames. Using bdrv_dirname() as the basis is better because
since we have BDS, we can descend through the BDS tree to the protocol
layer, which gives us a greater probability of finding a non-JSON name;
also, bdrv_dirname() is more correct as it allows block drivers to
override the generation of that directory name in a protocol-specific
way.
We still need to keep bdrv_get_full_backing_filename_from_filename(),
though, because it has valid callers which need it during image creation
when no BDS is available yet.
This makes a test case in qemu-iotest 110, which was supposed to fail,
work. That is actually good, but we need to change the reference output
(and the comment in 110) accordingly.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-20-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This function queries a node; since we cannot do that right now, it
executes query-named-block-nodes and returns the matching node's object.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20190201192935.18394-8-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190201192935.18394-7-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Basically, bdrv_refresh_filename() should respect all children of a
BlockDriverState. However, generally those children are driver-specific,
so this function cannot handle the general case. On the other hand,
there are only few drivers which use other children than @file and
@backing (that being vmdk, quorum, and blkverify).
Most block drivers only use @file and/or @backing (if they use any
children at all). Both can be implemented directly in
bdrv_refresh_filename.
The user overriding the file's filename is already handled, however, the
user overriding the backing file is not. If this is done, opening the
BDS with the plain filename of its file will not be correct, so we may
not set bs->exact_filename in that case.
iotest 051 contains test cases for overriding the backing file, and so
its output changes with this patch applied.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-6-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This is a simple move of Python code that wraps common QEMU
functionality, and are used by a number of different tests
and scripts.
By treating that code as a real Python module, we can more easily:
* reuse code
* have a proper place for the module's own unittests
* apply a more consistent style
* generate documentation
Signed-off-by: Cleber Rosa <crosa@redhat.com>
Reviewed-by: Caio Carrara <ccarrara@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20190206162901.19082-2-crosa@redhat.com>
Signed-off-by: Cleber Rosa <crosa@redhat.com>
Since qemu currently doesn't flush persistent bitmaps to disk until
shutdown (which might be MUCH later), it's useful if 'query-block'
at least shows WHICH bitmaps will (eventually) make it to persistent
storage. Update affected iotests.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20190204210512.27458-1-eblake@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
A new test file 242 added to the qemu-iotests set. It checks
the format of qcow2 specific information for the new added
section that lists details of bitmaps.
Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Message-Id: <1549638368-530182-4-git-send-email-andrey.shinkevich@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: pep8 compliance, avoid trailing blank line]
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
It's not enough to order the kwargs for consistent QMP log output,
we must also sort any sub-dictionaries in lists that appear as values.
Reported-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Without this filter, this test sometimes fails.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch forbids attaching a disk to a SCSI device if its using a
different AioContext. Test case included.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This fixes a crash when attaching two disks with the same blockdev to
a SCSI device that is using iothreads. Test case included.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This fixes a crash when attaching a disk to a SCSI device using
iothreads, then detaching it and reattaching it again. Test case
included.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Clarify that the number of extents provided in BlockdevCreateOptionsVmdk
must match the number of extents that will actually be used. Providing
more extents will result in an error now.
This requires adapting the test case to provide the right number of
extents.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
This test waits for a MIGRATION event with status=completed on the
source VM before querying the migration status on both source and
destination. However, just because the source says migration has
completed does not mean the destination thinks the same. Therefore, in
some cases, the destination VM may still report "active" instead of
"completed" when asked for its migration status.
Fix this by enabling migration events on both VMs and waiting until both
source and destination emit a status=completed MIGRATION event.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Recently, some bugs in dmg file have been fixed. To prevent reading dmg
is broken someday in the future, add a simple test which ensures the
conversion from dmg to raw should not hang or face any I/O error.
Signed-off-by: yuchenlin <npes87184@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The mirror_start_job() function used for the commit-active job blocks
the source, target and all intermediate nodes for the duration of the
job.
target <- intermediate <- source
Since 4ef85a9c23 this function creates a dummy mirror_top_bs that
goes on top of the source node, and it is this dummy node that gets
blocked instead. The source node is never blocked or added to the
job's list of nodes.
target <- intermediate <- source <- mirror_top
At the moment I don't think it is possible to exploit this problem
because any additional job on 'source' would either be forbidden for
other reasons or it would need to involve an additional node that is
blocked, causing an error.
This can be seen in the error messages, however, because they never
refer to the source node being blocked:
$ qemu-img create -f qcow2 hd0.qcow2 1M
$ qemu-img create -f qcow2 -b hd0.qcow2 hd1.qcow2
$ qemu-io -c 'write 0 1M' hd0.qcow2
$ $QEMU -drive if=none,file=hd1.qcow2,node-name=hd1
{ "execute": "qmp_capabilities" }
{ "execute": "block-commit", "arguments": {"device": "hd1", "speed": 256}}
{ "execute": "block-stream", "arguments": {"device": "hd1"}}
{ "error": {"class": "GenericError",
"desc": "Node 'hd0' is busy: block device is in use by block job: commit"}}
After this patch the error message refers to 'hd1', as it should.
The expected output of iotest 141 also needs to be updated for the
same reason.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
To do this, we need to allow creating the NBD server on various ports
instead of a single one (which may not even work if you run just one
instance, because something entirely else might be using that port).
So we just pick a random port in [32768, 32768 + 1024) and try to create
a server there. If that fails, we just retry until something sticks.
For the IPv6 test, we need a different range, though (just above that
one). This is because "localhost" resolves to both 127.0.0.1 and ::1.
This means that if you bind to it, it will bind to both, if possible, or
just one if the other is already in use. Therefore, if the IPv6 test
has already taken [::1]:some_port and we then try to take
localhost:some_port, that will work -- only the second server will be
bound to 127.0.0.1:some_port alone and not [::1]:some_port in addition.
So we have two different servers on the same port, one for IPv4 and one
for IPv6.
But when we then try to connect to the server through
localhost:some_port, we will always end up at the IPv6 one (as long as
it is up), and this may not be the one we want.
Thus, we must make sure not to create an IPv6-only NBD server on the
same port as a normal "dual-stack" NBD server -- which is done by using
distinct port ranges, as explained above.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20181221234750.23577-4-mreitz@redhat.com
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
By default, qemu-nbd binds to 0.0.0.0. However, we then proceed to
connect to "localhost". Usually, this works out fine; but if this test
is run concurrently, some other test function may have bound a different
server to ::1 (on the same port -- you can bind different serves to the
same port, as long as one is on IPv4 and the other on IPv6).
So running qemu-nbd works, it can bind to 0.0.0.0:NBD_PORT. But
potentially a concurrent test has successfully taken [::1]:NBD_PORT. In
this case, trying to connect to "localhost" will lead us to the IPv6
instance, where we do not want to end up.
Fix this by just binding to "localhost". This will make qemu-nbd error
out immediately and not give us cryptic errors later.
(Also, it will allow us to just try a different port as of a future
patch.)
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20181221234750.23577-3-mreitz@redhat.com
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
In some cases, we may want to deal with qemu-nbd errors (e.g. by
launching it in a different configuration until it no longer throws
any). In that case, we do not want its output ending up in the test
output.
It may still be useful for handling the error, though, so add a new
function that works basically like qemu_nbd(), only that it returns the
qemu-nbd output instead of making it end up in the log. In contrast to
qemu_img_pipe(), it does still return the exit code as well, though,
because that is even more important for error handling.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20181221234750.23577-2-mreitz@redhat.com
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Hot-unplug a scsi-hd using an iothread. The previous patch fixes a
segfault in this scenario.
This patch adds a regression test.
Suggested-by: Alberto Garcia <berto@igalia.com>
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190114133257.30299-3-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Any good new feature deserves some regression testing :)
Coverage includes:
- 223: what happens when there are 0 or more than 1 export,
proof that we can see multiple contexts including qemu:dirty-bitmap
- 233: proof that we can list over TLS, and that mix-and-match of
plain/TLS listings will behave sanely
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20190117193658.16413-22-eblake@redhat.com>
We have a race between the nbd server and the client both trying
to report errors at once which can make the test sometimes fail
if the output lines swap order under load. Break the race by
collecting server messages into a file and then replaying that
at the end of the test.
We may yet want to fix the server to not output ANYTHING for a
client action except when -v was used (to avoid malicious clients
from being able to DoS a server by filling up its logs), but that
is saved for a future patch.
Signed-off-by: Eric Blake <eblake@redhat.com>
CC: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20190117193658.16413-2-eblake@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Having to fire up qemu, then use QMP commands for nbd-server-start
and nbd-server-add, just to expose a persistent dirty bitmap, is
rather tedious. Make it possible to expose a dirty bitmap using
just qemu-nbd (of course, for now this only works when qemu-nbd is
visiting a BDS formatted as qcow2).
Of course, any good feature also needs unit testing, so expand
iotest 223 to cover it.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190111194720.15671-9-eblake@redhat.com>
With the experimental x-nbd-server-add-bitmap command, there was
a window of time where an NBD client could see the export but not
the associated dirty bitmap, which can cause a client that planned
on using the dirty bitmap to be forced to treat the entire image
as dirty as a safety fallback. Furthermore, if the QMP client
successfully exports a disk but then fails to add the bitmap, it
has to take on the burden of removing the export. Since we don't
allow changing the exposed dirty bitmap (whether to a different
bitmap, or removing advertisement of the bitmap), it is nicer to
make the bitmap tied to the export at the time the export is
created, with automatic failure to export if the bitmap is not
available.
The experimental command included an optional 'bitmap-export-name'
field for remapping the name exposed over NBD to be different from
the bitmap name stored on disk. However, my libvirt demo code
for implementing differential backups on top of persistent bitmaps
did not need to take advantage of that feature (it is instead
possible to create a new temporary bitmap with the desired name,
use block-dirty-bitmap-merge to merge one or more persistent
bitmaps into the temporary, then associate the temporary with the
NBD export, if control is needed over the exported bitmap name).
Hence, I'm not copying that part of the experiment over to the
stable addition. For more details on the libvirt demo, see
https://www.redhat.com/archives/libvir-list/2018-October/msg01254.html,
https://kvmforum2018.sched.com/event/FzuB/facilitating-incremental-backup-eric-blake-red-hat
This patch focuses on the user interface, and reduces (but does
not completely eliminate) the window where an NBD client can see
the export but not the dirty bitmap, with less work to clean up
after errors. Later patches will add further cleanups now that
this interface is declared stable via a single QMP command,
including removing the race window.
Update test 223 to use the new interface.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20190111194720.15671-6-eblake@redhat.com>
Our initial implementation of x-nbd-server-add-bitmap put
in a restriction because of incremental backups: in that
usage, we are exporting one qcow2 file (the temporary overlay
target of a blockdev-backup sync:none job) and a dirty bitmap
owned by a second qcow2 file (the source of the
blockdev-backup, which is the backing file of the temporary).
While both qcow2 files are still writable (the target in
order to capture copy-on-write of old contents, and the
source in order to track live guest writes in the meantime),
the NBD client expects to see constant data, including the
dirty bitmap. An enabled bitmap in the source would be
modified by guest writes, which is at odds with the NBD
export being a read-only constant view, hence the initial
code choice of enforcing a disabled bitmap (the intent is
that the exposed bitmap was disabled in the same transaction
that started the blockdev-backup job, although we don't want
to track enough state to actually enforce that).
However, consider the case of a bitmap contained in a read-only
node (including when the bitmap is found in a backing layer of
the active image). Because the node can't be modified, the
bitmap won't change due to writes, regardless of whether it is
still enabled. Forbidding the export unless the bitmap is
disabled is awkward, paritcularly since we can't change the
bitmap to be disabled (because the node is read-only).
Alternatively, consider the case of live storage migration,
where management directs the destination to create a writable
NBD server, then performs a drive-mirror from the source to
the target, prior to doing the rest of the live migration.
Since storage migration can be time-consuming, it may be wise
to let the destination include a dirty bitmap to track which
portions it has already received, where even if the migration
is interrupted and restarted, the source can query the
destination block status in order to potentially minimize
re-sending data that has not changed in the meantime on a
second attempt. Such code has not been written, and might not
be trivial (after all, a cluster being marked dirty in the
bitmap does not necessarily guarantee it has the desired
contents), but it makes sense that letting an active dirty
bitmap be exposed and changing alongside writes may prove
useful in the future.
Solve both issues by gating the restriction against a
disabled bitmap to only happen when the caller has requested
a read-only export, and where the BDS that owns the bitmap
(whether or not it is the BDS handed to nbd_export_new() or
from its backing chain) is still writable. We could drop
the check altogether (if management apps are prepared to
deal with a changing bitmap even on a read-only image), but
for now keeping a check for the read-only case still stands
a chance of preventing management errors.
Update iotest 223 to show the looser behavior by leaving
a bitmap enabled the whole run; note that we have to tear
down and re-export a node when handling an error.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190111194720.15671-4-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Since we already forbid other nbd-server commands when not
in the right state, it is unlikely that any caller was relying
on a second stop to behave as a silent no-op. Update iotest
223 to show the improved behavior.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190111194720.15671-3-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Peter Maydell
Daniel P. Berrangé
Andrey Shinkevich
Max Reitz
Stefan Hajnoczi
Cleber Rosa
Eric Blake
John Snow
Alberto Garcia
Kevin Wolf
Fam Zheng
yuchenlin