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[PATCH 44/55] iotests: Test large write request to qcow2 file
From: |
Michael Roth |
Subject: |
[PATCH 44/55] iotests: Test large write request to qcow2 file |
Date: |
Tue, 5 Nov 2019 14:52:32 -0600 |
From: Max Reitz <address@hidden>
Without HEAD^, the following happens when you attempt a large write
request to a qcow2 file such that the number of bytes covered by all
clusters involved in a single allocation will exceed INT_MAX:
(A) handle_alloc_space() decides to fill the whole area with zeroes and
fails because bdrv_co_pwrite_zeroes() fails (the request is too
large).
(B) If handle_alloc_space() does not do anything, but merge_cow()
decides that the requests can be merged, it will create a too long
IOV that later cannot be written.
(C) Otherwise, all parts will be written separately, so those requests
will work.
In either B or C, though, qcow2_alloc_cluster_link_l2() will have an
overflow: We use an int (i) to iterate over nb_clusters, and then
calculate the L2 entry based on "i << s->cluster_bits" -- which will
overflow if the range covers more than INT_MAX bytes. This then leads
to image corruption because the L2 entry will be wrong (it will be
recognized as a compressed cluster).
Even if that were not the case, the .cow_end area would be empty
(because handle_alloc() will cap avail_bytes and nb_bytes at INT_MAX, so
their difference (which is the .cow_end size) will be 0).
So this test checks that on such large requests, the image will not be
corrupted. Unfortunately, we cannot check whether COW will be handled
correctly, because that data is discarded when it is written to null-co
(but we have to use null-co, because writing 2 GB of data in a test is
not quite reasonable).
Signed-off-by: Max Reitz <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
Signed-off-by: Kevin Wolf <address@hidden>
(cherry picked from commit a1406a9262a087d9ec9627b88da13c4590b61dae)
Conflicts:
tests/qemu-iotests/group
*drop context dep. on tests not in 4.1
Signed-off-by: Michael Roth <address@hidden>
---
tests/qemu-iotests/270 | 83 ++++++++++++++++++++++++++++++++++++++
tests/qemu-iotests/270.out | 9 +++++
tests/qemu-iotests/group | 1 +
3 files changed, 93 insertions(+)
create mode 100755 tests/qemu-iotests/270
create mode 100644 tests/qemu-iotests/270.out
diff --git a/tests/qemu-iotests/270 b/tests/qemu-iotests/270
new file mode 100755
index 0000000000..b9a12b908c
--- /dev/null
+++ b/tests/qemu-iotests/270
@@ -0,0 +1,83 @@
+#!/usr/bin/env bash
+#
+# Test large write to a qcow2 image
+#
+# Copyright (C) 2019 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/>.
+#
+
+seq=$(basename "$0")
+echo "QA output created by $seq"
+
+status=1 # failure is the default!
+
+_cleanup()
+{
+ _cleanup_test_img
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+
+# This is a qcow2 regression test
+_supported_fmt qcow2
+_supported_proto file
+_supported_os Linux
+
+# We use our own external data file and our own cluster size, and we
+# require v3 images
+_unsupported_imgopts data_file cluster_size 'compat=0.10'
+
+
+# We need a backing file so that handle_alloc_space() will not do
+# anything. (If it were to do anything, it would simply fail its
+# write-zeroes request because the request range is too large.)
+TEST_IMG="$TEST_IMG.base" _make_test_img 4G
+$QEMU_IO -c 'write 0 512' "$TEST_IMG.base" | _filter_qemu_io
+
+# (Use .orig because _cleanup_test_img will remove that file)
+# We need a large cluster size, see below for why (above the $QEMU_IO
+# invocation)
+_make_test_img -o cluster_size=2M,data_file="$TEST_IMG.orig" \
+ -b "$TEST_IMG.base" 4G
+
+# We want a null-co as the data file, because it allows us to quickly
+# "write" 2G of data without using any space.
+# (qemu-img create does not like it, though, because null-co does not
+# support image creation.)
+$QEMU_IMG amend -o data_file="json:{'driver':'null-co',,'size':'4294967296'}" \
+ "$TEST_IMG"
+
+# This gives us a range of:
+# 2^31 - 512 + 768 - 1 = 2^31 + 255 > 2^31
+# until the beginning of the end COW block. (The total allocation
+# size depends on the cluster size, but all that is important is that
+# it exceeds INT_MAX.)
+#
+# 2^31 - 512 is the maximum request size. We want this to result in a
+# single allocation, and because the qcow2 driver splits allocations
+# on L2 boundaries, we need large L2 tables; hence the cluster size of
+# 2 MB. (Anything from 256 kB should work, though, because then one L2
+# table covers 8 GB.)
+$QEMU_IO -c "write 768 $((2 ** 31 - 512))" "$TEST_IMG" | _filter_qemu_io
+
+_check_test_img
+
+# success, all done
+echo "*** done"
+rm -f $seq.full
+status=0
diff --git a/tests/qemu-iotests/270.out b/tests/qemu-iotests/270.out
new file mode 100644
index 0000000000..c7be111014
--- /dev/null
+++ b/tests/qemu-iotests/270.out
@@ -0,0 +1,9 @@
+QA output created by 270
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=4294967296
+wrote 512/512 bytes at offset 0
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=4294967296
backing_file=TEST_DIR/t.IMGFMT.base data_file=TEST_DIR/t.IMGFMT.orig
+wrote 2147483136/2147483136 bytes at offset 768
+2 GiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+No errors were found on the image.
+*** done
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 8bc2f3857d..7629e8ea17 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -274,3 +274,4 @@
265 rw auto quick
266 rw quick
267 rw auto quick snapshot
+270 rw backing quick
--
2.17.1
- [PATCH 02/55] Revert "ide/ahci: Check for -ECANCELED in aio callbacks", (continued)
- [PATCH 02/55] Revert "ide/ahci: Check for -ECANCELED in aio callbacks", Michael Roth, 2019/11/05
- [PATCH 22/55] block/nfs: tear down aio before nfs_close, Michael Roth, 2019/11/05
- [PATCH 31/55] coroutine: Add qemu_co_mutex_assert_locked(), Michael Roth, 2019/11/05
- [PATCH 33/55] block/backup: fix max_transfer handling for copy_range, Michael Roth, 2019/11/05
- [PATCH 38/55] s390: PCI: fix IOMMU region init, Michael Roth, 2019/11/05
- [PATCH 35/55] hw/arm/boot.c: Set NSACR.{CP11, CP10} for NS kernel boots, Michael Roth, 2019/11/05
- [PATCH 34/55] block/backup: fix backup_cow_with_offload for last cluster, Michael Roth, 2019/11/05
- [PATCH 39/55] block/snapshot: Restrict set of snapshot nodes, Michael Roth, 2019/11/05
- [PATCH 03/55] s390x/tcg: Fix VERIM with 32/64 bit elements, Michael Roth, 2019/11/05
- [PATCH 43/55] qcow2: Limit total allocation range to INT_MAX, Michael Roth, 2019/11/05
- [PATCH 44/55] iotests: Test large write request to qcow2 file,
Michael Roth <=
- [PATCH 47/55] virtio: new post_load hook, Michael Roth, 2019/11/05
- [PATCH 07/55] xen-bus: check whether the frontend is active during device reset..., Michael Roth, 2019/11/05
- [PATCH 48/55] virtio-net: prevent offloads reset on migration, Michael Roth, 2019/11/05
- [PATCH 42/55] hw/core/loader: Fix possible crash in rom_copy(), Michael Roth, 2019/11/05
- [PATCH 45/55] mirror: Do not dereference invalid pointers, Michael Roth, 2019/11/05
- [PATCH 52/55] target/arm: Allow reading flags from FPSCR for M-profile, Michael Roth, 2019/11/05
- [PATCH 46/55] ui: Fix hanging up Cocoa display on macOS 10.15 (Catalina), Michael Roth, 2019/11/05
- [PATCH 50/55] util/hbitmap: strict hbitmap_reset, Michael Roth, 2019/11/05
- [PATCH 55/55] virtio-blk: Cancel the pending BH when the dataplane is reset, Michael Roth, 2019/11/05
- [PATCH 05/55] pc: Don't make die-id mandatory unless necessary, Michael Roth, 2019/11/05