From 0ba4c0836f702bb3abbd173c7ee486a8247331ae Mon Sep 17 00:00:00 2001 From: Hanna Reitz Date: Tue, 18 Jan 2022 18:00:00 +0100 Subject: [PATCH 7/7] iotests/block-status-cache: New test RH-Author: Hanna Reitz RH-MergeRequest: 112: block/io: Update BSC only if want_zero is true RH-Commit: [2/2] ba86b4db32c33e17a85f476d445ef0523cf8f60e RH-Bugzilla: 2041480 RH-Acked-by: Eric Blake RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Kevin Wolf 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 Message-Id: <20220118170000.49423-3-hreitz@redhat.com> Reviewed-by: Nir Soffer Reviewed-by: Eric Blake Tested-by: Eric Blake Signed-off-by: Eric Blake (cherry picked from commit 6384dd534d742123d26c008d9794b20bc41359d5) Signed-off-by: Hanna Reitz --- 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 . +# + +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 -- 2.27.0