| Message ID | 20220118170000.49423-3-hreitz@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | block/io: Update BSC only if want_zero is true | expand |
On Tue, Jan 18, 2022 at 7:12 PM Hanna Reitz <hreitz@redhat.com> wrote: > > Add a new test to verify that want_zero=false block-status calls do not > pollute the block-status cache for want_zero=true calls. > > We check want_zero=true calls and their results using `qemu-img map` > (over NBD), and want_zero=false calls also using `qemu-img map` over > NBD, but using the qemu:allocation-depth context. > > (This test case cannot be integrated into nbd-qemu-allocation, because > that is a qcow2 test, and this is a raw test.) > > Signed-off-by: Hanna Reitz <hreitz@redhat.com> > --- > tests/qemu-iotests/tests/block-status-cache | 139 ++++++++++++++++++ > .../qemu-iotests/tests/block-status-cache.out | 5 + > 2 files changed, 144 insertions(+) > create mode 100755 tests/qemu-iotests/tests/block-status-cache > create mode 100644 tests/qemu-iotests/tests/block-status-cache.out > > diff --git a/tests/qemu-iotests/tests/block-status-cache b/tests/qemu-iotests/tests/block-status-cache > new file mode 100755 > index 0000000000..6fa10bb8f8 > --- /dev/null > +++ b/tests/qemu-iotests/tests/block-status-cache > @@ -0,0 +1,139 @@ > +#!/usr/bin/env python3 > +# group: rw quick > +# > +# Test cases for the block-status cache. > +# > +# Copyright (C) 2022 Red Hat, Inc. > +# > +# This program is free software; you can redistribute it and/or modify > +# it under the terms of the GNU General Public License as published by > +# the Free Software Foundation; either version 2 of the License, or > +# (at your option) any later version. > +# > +# This program is distributed in the hope that it will be useful, > +# but WITHOUT ANY WARRANTY; without even the implied warranty of > +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > +# GNU General Public License for more details. > +# > +# You should have received a copy of the GNU General Public License > +# along with this program. If not, see <http://www.gnu.org/licenses/>. > +# > + > +import os > +import signal > +import iotests > +from iotests import qemu_img_create, qemu_img_pipe, qemu_nbd > + > + > +image_size = 1 * 1024 * 1024 > +test_img = os.path.join(iotests.test_dir, 'test.img') > + > +nbd_pidfile = os.path.join(iotests.test_dir, 'nbd.pid') > +nbd_sock = os.path.join(iotests.sock_dir, 'nbd.sock') > + > + > +class TestBscWithNbd(iotests.QMPTestCase): > + def setUp(self) -> None: > + """Just create an empty image with a read-only NBD server on it""" > + assert qemu_img_create('-f', iotests.imgfmt, test_img, > + str(image_size)) == 0 > + > + # Pass --allocation-depth to enable the qemu:allocation-depth context, > + # which we are going to query to provoke a block-status inquiry with > + # want_zero=false. > + assert qemu_nbd(f'--socket={nbd_sock}', > + f'--format={iotests.imgfmt}', > + '--persistent', > + '--allocation-depth', > + '--read-only', > + f'--pid-file={nbd_pidfile}', > + test_img) \ > + == 0 > + > + def tearDown(self) -> None: > + with open(nbd_pidfile, encoding='utf-8') as f: > + pid = int(f.read()) > + os.kill(pid, signal.SIGTERM) > + os.remove(nbd_pidfile) > + os.remove(test_img) > + > + def test_with_zero_bug(self) -> None: > + """ > + Verify that the block-status cache is not corrupted by a > + want_zero=false call. > + We can provoke a want_zero=false call with `qemu-img map` over NBD with > + x-dirty-bitmap=qemu:allocation-depth, so we first run a normal `map` > + (which results in want_zero=true), then using said > + qemu:allocation-depth context, and finally another normal `map` to > + verify that the cache has not been corrupted. > + """ > + > + nbd_img_opts = f'driver=nbd,server.type=unix,server.path={nbd_sock}' > + nbd_img_opts_alloc_depth = nbd_img_opts + \ > + ',x-dirty-bitmap=qemu:allocation-depth' > + > + # Normal map, results in want_zero=true. > + # This will probably detect an allocated data sector first (qemu likes > + # to allocate the first sector to facilitate alignment probing), and > + # then the rest to be zero. The BSC will thus contain (if anything) > + # one range covering the first sector. > + map_pre = qemu_img_pipe('map', '--output=json', '--image-opts', > + nbd_img_opts) > + > + # qemu:allocation-depth maps for want_zero=false. > + # want_zero=false should (with the file driver, which the server is > + # using) report everything as data. While this is sufficient for > + # want_zero=false, this is nothing that should end up in the > + # block-status cache. > + # Due to a bug, this information did end up in the cache, though, and > + # this would lead to wrong information being returned on subsequent > + # want_zero=true calls. > + # > + # We need to run this map twice: On the first call, we probably still > + # have the first sector in the cache, and so this will be served from > + # the cache; and only the subsequent range will be queried from the > + # block driver. This subsequent range will then be entered into the > + # cache. > + # If we did a want_zero=true call at this point, we would thus get > + # correct information: The first sector is not covered by the cache, so > + # we would get fresh block-status information from the driver, which > + # would return a data range, and this would then go into the cache, > + # evicting the wrong range from the want_zero=false call before. > + # > + # Therefore, we need a second want_zero=false map to reproduce: > + # Since the first sector is not in the cache, the query for its status > + # will go to the driver, which will return a result that reports the > + # whole image to be a single data area. This result will then go into > + # the cache, and so the cache will then report the whole image to > + # contain data. > + # > + # Note that once the cache reports the whole image to contain data, any > + # subsequent map operation will be served from the cache, and so we can > + # never loop too many times here. > + for _ in range(2): > + # (Ignore the result, this is just to contaminate the cache) > + qemu_img_pipe('map', '--output=json', '--image-opts', > + nbd_img_opts_alloc_depth) > + > + # Now let's see whether the cache reports everything as data, or > + # whether we get correct information (i.e. the same as we got on our > + # first attempt). > + map_post = qemu_img_pipe('map', '--output=json', '--image-opts', > + nbd_img_opts) > + > + if map_pre != map_post: > + print('ERROR: Map information differs before and after querying ' + > + 'qemu:allocation-depth') > + print('Before:') > + print(map_pre) > + print('After:') > + print(map_post) > + > + self.fail("Map information differs") > + > + > +if __name__ == '__main__': > + # The block-status cache only works on the protocol layer, so to test it, > + # we can only use the raw format > + iotests.main(supported_fmts=['raw'], > + supported_protocols=['file']) > diff --git a/tests/qemu-iotests/tests/block-status-cache.out b/tests/qemu-iotests/tests/block-status-cache.out > new file mode 100644 > index 0000000000..ae1213e6f8 > --- /dev/null > +++ b/tests/qemu-iotests/tests/block-status-cache.out > @@ -0,0 +1,5 @@ > +. > +---------------------------------------------------------------------- > +Ran 1 tests > + > +OK > -- > 2.33.1 > The out file is not very useful, and even fragile - if the test framework will change the output format, the test will fail. Ideally we depend only on the relevant output of our tools, and using a different version of the test framework on replacing it (e.g pytest) will not require modifying the out files. Regardless I would like to see this fix merged and this issue already exists in other tests. Some tests in tests/ do have useful output that can make debugging failures easier. Reviewed-by: Nir Soffer <nsoffer@redhat.com>
On Tue, Jan 18, 2022 at 06:00:00PM +0100, Hanna Reitz wrote: > Add a new test to verify that want_zero=false block-status calls do not > pollute the block-status cache for want_zero=true calls. > > We check want_zero=true calls and their results using `qemu-img map` > (over NBD), and want_zero=false calls also using `qemu-img map` over > NBD, but using the qemu:allocation-depth context. > > (This test case cannot be integrated into nbd-qemu-allocation, because > that is a qcow2 test, and this is a raw test.) > > Signed-off-by: Hanna Reitz <hreitz@redhat.com> > --- > tests/qemu-iotests/tests/block-status-cache | 139 ++++++++++++++++++ > .../qemu-iotests/tests/block-status-cache.out | 5 + > 2 files changed, 144 insertions(+) > create mode 100755 tests/qemu-iotests/tests/block-status-cache > create mode 100644 tests/qemu-iotests/tests/block-status-cache.out Reviewed-by: Eric Blake <eblake@redhat.com> As this was detected as a regression using NBD, I'm happy to add this to my NBD queue, and will send a pull request soon.
On Fri, Jan 28, 2022 at 02:50:51PM -0600, Eric Blake wrote: > On Tue, Jan 18, 2022 at 06:00:00PM +0100, Hanna Reitz wrote: > > Add a new test to verify that want_zero=false block-status calls do not > > pollute the block-status cache for want_zero=true calls. > > > > We check want_zero=true calls and their results using `qemu-img map` > > (over NBD), and want_zero=false calls also using `qemu-img map` over > > NBD, but using the qemu:allocation-depth context. > > > > (This test case cannot be integrated into nbd-qemu-allocation, because > > that is a qcow2 test, and this is a raw test.) > > > > Signed-off-by: Hanna Reitz <hreitz@redhat.com> > > --- > > tests/qemu-iotests/tests/block-status-cache | 139 ++++++++++++++++++ > > .../qemu-iotests/tests/block-status-cache.out | 5 + > > 2 files changed, 144 insertions(+) > > create mode 100755 tests/qemu-iotests/tests/block-status-cache > > create mode 100644 tests/qemu-iotests/tests/block-status-cache.out > > Reviewed-by: Eric Blake <eblake@redhat.com> I also tested that applying this patch but not 1/2 reproduces the failure for me, so I'm adding: Tested-by: Eric Blake <eblake@redhat.com>
diff --git a/tests/qemu-iotests/tests/block-status-cache b/tests/qemu-iotests/tests/block-status-cache new file mode 100755 index 0000000000..6fa10bb8f8 --- /dev/null +++ b/tests/qemu-iotests/tests/block-status-cache @@ -0,0 +1,139 @@ +#!/usr/bin/env python3 +# group: rw quick +# +# Test cases for the block-status cache. +# +# Copyright (C) 2022 Red Hat, Inc. +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 2 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. +# + +import os +import signal +import iotests +from iotests import qemu_img_create, qemu_img_pipe, qemu_nbd + + +image_size = 1 * 1024 * 1024 +test_img = os.path.join(iotests.test_dir, 'test.img') + +nbd_pidfile = os.path.join(iotests.test_dir, 'nbd.pid') +nbd_sock = os.path.join(iotests.sock_dir, 'nbd.sock') + + +class TestBscWithNbd(iotests.QMPTestCase): + def setUp(self) -> None: + """Just create an empty image with a read-only NBD server on it""" + assert qemu_img_create('-f', iotests.imgfmt, test_img, + str(image_size)) == 0 + + # Pass --allocation-depth to enable the qemu:allocation-depth context, + # which we are going to query to provoke a block-status inquiry with + # want_zero=false. + assert qemu_nbd(f'--socket={nbd_sock}', + f'--format={iotests.imgfmt}', + '--persistent', + '--allocation-depth', + '--read-only', + f'--pid-file={nbd_pidfile}', + test_img) \ + == 0 + + def tearDown(self) -> None: + with open(nbd_pidfile, encoding='utf-8') as f: + pid = int(f.read()) + os.kill(pid, signal.SIGTERM) + os.remove(nbd_pidfile) + os.remove(test_img) + + def test_with_zero_bug(self) -> None: + """ + Verify that the block-status cache is not corrupted by a + want_zero=false call. + We can provoke a want_zero=false call with `qemu-img map` over NBD with + x-dirty-bitmap=qemu:allocation-depth, so we first run a normal `map` + (which results in want_zero=true), then using said + qemu:allocation-depth context, and finally another normal `map` to + verify that the cache has not been corrupted. + """ + + nbd_img_opts = f'driver=nbd,server.type=unix,server.path={nbd_sock}' + nbd_img_opts_alloc_depth = nbd_img_opts + \ + ',x-dirty-bitmap=qemu:allocation-depth' + + # Normal map, results in want_zero=true. + # This will probably detect an allocated data sector first (qemu likes + # to allocate the first sector to facilitate alignment probing), and + # then the rest to be zero. The BSC will thus contain (if anything) + # one range covering the first sector. + map_pre = qemu_img_pipe('map', '--output=json', '--image-opts', + nbd_img_opts) + + # qemu:allocation-depth maps for want_zero=false. + # want_zero=false should (with the file driver, which the server is + # using) report everything as data. While this is sufficient for + # want_zero=false, this is nothing that should end up in the + # block-status cache. + # Due to a bug, this information did end up in the cache, though, and + # this would lead to wrong information being returned on subsequent + # want_zero=true calls. + # + # We need to run this map twice: On the first call, we probably still + # have the first sector in the cache, and so this will be served from + # the cache; and only the subsequent range will be queried from the + # block driver. This subsequent range will then be entered into the + # cache. + # If we did a want_zero=true call at this point, we would thus get + # correct information: The first sector is not covered by the cache, so + # we would get fresh block-status information from the driver, which + # would return a data range, and this would then go into the cache, + # evicting the wrong range from the want_zero=false call before. + # + # Therefore, we need a second want_zero=false map to reproduce: + # Since the first sector is not in the cache, the query for its status + # will go to the driver, which will return a result that reports the + # whole image to be a single data area. This result will then go into + # the cache, and so the cache will then report the whole image to + # contain data. + # + # Note that once the cache reports the whole image to contain data, any + # subsequent map operation will be served from the cache, and so we can + # never loop too many times here. + for _ in range(2): + # (Ignore the result, this is just to contaminate the cache) + qemu_img_pipe('map', '--output=json', '--image-opts', + nbd_img_opts_alloc_depth) + + # Now let's see whether the cache reports everything as data, or + # whether we get correct information (i.e. the same as we got on our + # first attempt). + map_post = qemu_img_pipe('map', '--output=json', '--image-opts', + nbd_img_opts) + + if map_pre != map_post: + print('ERROR: Map information differs before and after querying ' + + 'qemu:allocation-depth') + print('Before:') + print(map_pre) + print('After:') + print(map_post) + + self.fail("Map information differs") + + +if __name__ == '__main__': + # The block-status cache only works on the protocol layer, so to test it, + # we can only use the raw format + iotests.main(supported_fmts=['raw'], + supported_protocols=['file']) diff --git a/tests/qemu-iotests/tests/block-status-cache.out b/tests/qemu-iotests/tests/block-status-cache.out new file mode 100644 index 0000000000..ae1213e6f8 --- /dev/null +++ b/tests/qemu-iotests/tests/block-status-cache.out @@ -0,0 +1,5 @@ +. +---------------------------------------------------------------------- +Ran 1 tests + +OK
Add a new test to verify that want_zero=false block-status calls do not pollute the block-status cache for want_zero=true calls. We check want_zero=true calls and their results using `qemu-img map` (over NBD), and want_zero=false calls also using `qemu-img map` over NBD, but using the qemu:allocation-depth context. (This test case cannot be integrated into nbd-qemu-allocation, because that is a qcow2 test, and this is a raw test.) Signed-off-by: Hanna Reitz <hreitz@redhat.com> --- tests/qemu-iotests/tests/block-status-cache | 139 ++++++++++++++++++ .../qemu-iotests/tests/block-status-cache.out | 5 + 2 files changed, 144 insertions(+) create mode 100755 tests/qemu-iotests/tests/block-status-cache create mode 100644 tests/qemu-iotests/tests/block-status-cache.out