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9ffd6d646d
One clear problem with how qcow2's refcount structure rebuild algorithm
used to be before "qcow2: Improve refcount structure rebuilding" was
that it is prone to failure for qcow2 images on block devices: There is
generally unused space after the actual image, and if that exceeds what
one refblock covers, the old algorithm would invariably write the
reftable past the block device's end, which cannot work. The new
algorithm does not have this problem.
Test it with three tests:
(1) Create an image with more empty space at the end than what one
refblock covers, see whether rebuilding the refcount structures
results in a change in the image file length. (It should not.)
(2) Leave precisely enough space somewhere at the beginning of the image
for the new reftable (and the refblock for that place), see whether
the new algorithm puts the reftable there. (It should.)
(3) Test the original problem: Create (something like) a block device
with a fixed size, then create a qcow2 image in there, write some
data, and then have qemu-img check rebuild the refcount structures.
Before HEAD^, the reftable would have been written past the image
file end, i.e. outside of what the block device provides, which
cannot work. HEAD^ should have fixed that.
("Something like a block device" means a loop device if we can use
one ("sudo -n losetup" works), or a FUSE block export with
growable=false otherwise.)
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220405134652.19278-3-hreitz@redhat.com>
402 lines
13 KiB
Bash
Executable File
402 lines
13 KiB
Bash
Executable File
#!/usr/bin/env bash
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# group: rw auto quick
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#
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# Test case for repairing qcow2 images which cannot be repaired using
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# the on-disk refcount structures
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#
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# Copyright (C) 2014 Red Hat, Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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# creator
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owner=hreitz@redhat.com
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seq="$(basename $0)"
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echo "QA output created by $seq"
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status=1 # failure is the default!
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_cleanup()
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{
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_cleanup_test_img
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if [ -f "$TEST_DIR/qsd.pid" ]; then
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qsd_pid=$(cat "$TEST_DIR/qsd.pid")
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kill -KILL "$qsd_pid"
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fusermount -u "$TEST_DIR/fuse-export" &>/dev/null
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fi
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rm -f "$TEST_DIR/fuse-export"
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}
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trap "_cleanup; exit \$status" 0 1 2 3 15
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# get standard environment, filters and checks
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. ./common.rc
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. ./common.filter
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. ./common.qemu
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# This tests qcow2-specific low-level functionality
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_supported_fmt qcow2
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_supported_proto file fuse
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_supported_os Linux
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# This test directly modifies a refblock so it relies on refcount_bits being 16;
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# and the low-level modification it performs are not tuned for external data
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# files
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_unsupported_imgopts 'refcount_bits=\([^1]\|.\([^6]\|$\)\)' data_file
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# This test either needs sudo -n losetup or FUSE exports to work
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if sudo -n losetup &>/dev/null; then
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loopdev=true
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else
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loopdev=false
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# QSD --export fuse will either yield "Parameter 'id' is missing"
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# or "Invalid parameter 'fuse'", depending on whether there is
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# FUSE support or not.
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error=$($QSD --export fuse 2>&1)
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if [[ $error = *"'fuse'"* ]]; then
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_notrun 'Passwordless sudo for losetup or FUSE support required, but' \
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'neither is available'
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fi
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fi
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echo
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echo '=== Repairing an image without any refcount table ==='
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echo
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_make_test_img 64M
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# just write some data
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$QEMU_IO -c 'write -P 42 0 64k' "$TEST_IMG" | _filter_qemu_io
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# refcount_table_offset
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poke_file "$TEST_IMG" $((0x30)) "\x00\x00\x00\x00\x00\x00\x00\x00"
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# refcount_table_clusters
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poke_file "$TEST_IMG" $((0x38)) "\x00\x00\x00\x00"
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_check_test_img -r all
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$QEMU_IO -c 'read -P 42 0 64k' "$TEST_IMG" | _filter_qemu_io
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echo
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echo '=== Repairing unreferenced data cluster in new refblock area ==='
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echo
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_make_test_img -o 'cluster_size=512' 64M
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# Allocate the first 128 kB in the image (first refblock)
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$QEMU_IO -c 'write 0 0x1b200' "$TEST_IMG" | _filter_qemu_io
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# should be 131072 == 0x20000
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stat -c '%s' "$TEST_IMG"
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# Enter a cluster at 128 kB (0x20000)
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# XXX: This should be the first free entry in the last L2 table, but we cannot
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# be certain
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poke_file "$TEST_IMG" $((0x1ccc8)) "\x80\x00\x00\x00\x00\x02\x00\x00"
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# Fill the cluster
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truncate -s $((0x20200)) "$TEST_IMG"
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$QEMU_IO -c "open -o driver=raw $TEST_IMG" -c 'write -P 42 128k 512' \
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| _filter_qemu_io
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# The data should now appear at this guest offset
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$QEMU_IO -c 'read -P 42 0x1b200 512' "$TEST_IMG" | _filter_qemu_io
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# This cluster is unallocated; fix it
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_check_test_img -r all
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# This repair operation must have allocated a new refblock; and that refblock
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# should not overlap with the unallocated data cluster. If it does, the data
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# will be damaged, so check it.
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$QEMU_IO -c 'read -P 42 0x1b200 512' "$TEST_IMG" | _filter_qemu_io
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echo
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echo '=== Repairing refblock beyond the image end ==='
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echo
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echo
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echo '--- Otherwise clean ---'
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echo
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_make_test_img 64M
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# Normally, qemu doesn't create empty refblocks, so we just have to do it by
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# hand
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# XXX: This should be the entry for the second refblock
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poke_file "$TEST_IMG" $((0x10008)) "\x00\x00\x00\x00\x00\x10\x00\x00"
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# Mark that refblock as used
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# XXX: This should be the 17th entry (cluster 16) of the first
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# refblock
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poke_file "$TEST_IMG" $((0x20020)) "\x00\x01"
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_check_test_img -r all
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echo
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echo '--- Refblock is unallocated ---'
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echo
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_make_test_img 64M
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poke_file "$TEST_IMG" $((0x10008)) "\x00\x00\x00\x00\x00\x10\x00\x00"
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_check_test_img -r all
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echo
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echo '--- Signed overflow after the refblock ---'
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echo
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_make_test_img 64M
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poke_file "$TEST_IMG" $((0x10008)) "\x7f\xff\xff\xff\xff\xff\x00\x00"
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_check_test_img -r all
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echo
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echo '--- Unsigned overflow after the refblock ---'
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echo
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_make_test_img 64M
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poke_file "$TEST_IMG" $((0x10008)) "\xff\xff\xff\xff\xff\xff\x00\x00"
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_check_test_img -r all
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echo
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echo '=== Check rebuilt reftable location ==='
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# In an earlier version of the refcount rebuild algorithm, the
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# reftable was generally placed at the image end (unless something was
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# allocated in the area covered by the refblock right before the image
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# file end, then we would try to place the reftable in that refblock).
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# This was later changed so the reftable would be placed in the
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# earliest possible location. Test this.
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echo
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echo '--- Does the image size increase? ---'
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echo
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# First test: Just create some image, write some data to it, and
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# resize it so there is free space at the end of the image (enough
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# that it spans at least one full refblock, which for cluster_size=512
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# images, spans 128k). With the old algorithm, the reftable would
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# have then been placed at the end of the image file, but with the new
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# one, it will be put in that free space.
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# We want to check whether the size of the image file increases due to
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# rebuilding the refcount structures (it should not).
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_make_test_img -o 'cluster_size=512' 1M
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# Write something
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$QEMU_IO -c 'write 0 64k' "$TEST_IMG" | _filter_qemu_io
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# Add free space
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file_len=$(stat -c '%s' "$TEST_IMG")
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truncate -s $((file_len + 256 * 1024)) "$TEST_IMG"
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# Corrupt the image by saying the image header was not allocated
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rt_offset=$(peek_file_be "$TEST_IMG" 48 8)
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rb_offset=$(peek_file_be "$TEST_IMG" $rt_offset 8)
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poke_file "$TEST_IMG" $rb_offset "\x00\x00"
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# Check whether rebuilding the refcount structures increases the image
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# file size
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file_len=$(stat -c '%s' "$TEST_IMG")
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echo
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# The only leaks there can be are the old refcount structures that are
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# leaked during rebuilding, no need to clutter the output with them
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_check_test_img -r all | grep -v '^Repairing cluster.*refcount=1 reference=0'
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echo
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post_repair_file_len=$(stat -c '%s' "$TEST_IMG")
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if [[ $file_len -eq $post_repair_file_len ]]; then
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echo 'OK: Image size did not change'
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else
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echo 'ERROR: Image size differs' \
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"($file_len before, $post_repair_file_len after)"
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fi
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echo
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echo '--- Will the reftable occupy a hole specifically left for it? ---'
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echo
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# Note: With cluster_size=512, every refblock covers 128k.
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# The reftable covers 8M per reftable cluster.
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# Create an image that requires two reftable clusters (just because
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# this is more interesting than a single-clustered reftable).
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_make_test_img -o 'cluster_size=512' 9M
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$QEMU_IO -c 'write 0 8M' "$TEST_IMG" | _filter_qemu_io
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# Writing 8M will have resized the reftable. Unfortunately, doing so
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# will leave holes in the file, so we need to fill them up so we can
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# be sure the whole file is allocated. Do that by writing
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# consecutively smaller chunks starting from 8 MB, until the file
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# length increases even with a chunk size of 512. Then we must have
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# filled all holes.
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ofs=$((8 * 1024 * 1024))
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block_len=$((16 * 1024))
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while [[ $block_len -ge 512 ]]; do
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file_len=$(stat -c '%s' "$TEST_IMG")
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while [[ $(stat -c '%s' "$TEST_IMG") -eq $file_len ]]; do
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# Do not include this in the reference output, it does not
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# really matter which qemu-io calls we do here exactly
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$QEMU_IO -c "write $ofs $block_len" "$TEST_IMG" >/dev/null
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ofs=$((ofs + block_len))
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done
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block_len=$((block_len / 2))
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done
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# Fill up to 9M (do not include this in the reference output either,
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# $ofs is random for all we know)
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$QEMU_IO -c "write $ofs $((9 * 1024 * 1024 - ofs))" "$TEST_IMG" >/dev/null
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# Make space as follows:
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# - For the first refblock: Right at the beginning of the image (this
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# refblock is placed in the first place possible),
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# - For the reftable somewhere soon afterwards, still near the
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# beginning of the image (i.e. covered by the first refblock); the
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# reftable too is placed in the first place possible, but only after
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# all refblocks have been placed)
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# No space is needed for the other refblocks, because no refblock is
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# put before the space it covers. In this test case, we do not mind
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# if they are placed at the image file's end.
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# Before we make that space, we have to find out the host offset of
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# the area that belonged to the two data clusters at guest offset 4k,
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# because we expect the reftable to be placed there, and we will have
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# to verify that it is.
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l1_offset=$(peek_file_be "$TEST_IMG" 40 8)
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l2_offset=$(peek_file_be "$TEST_IMG" $l1_offset 8)
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l2_offset=$((l2_offset & 0x00fffffffffffe00))
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data_4k_offset=$(peek_file_be "$TEST_IMG" \
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$((l2_offset + 4096 / 512 * 8)) 8)
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data_4k_offset=$((data_4k_offset & 0x00fffffffffffe00))
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$QEMU_IO -c "discard 0 512" -c "discard 4k 1k" "$TEST_IMG" | _filter_qemu_io
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# Corrupt the image by saying the image header was not allocated
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rt_offset=$(peek_file_be "$TEST_IMG" 48 8)
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rb_offset=$(peek_file_be "$TEST_IMG" $rt_offset 8)
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poke_file "$TEST_IMG" $rb_offset "\x00\x00"
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echo
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# The only leaks there can be are the old refcount structures that are
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# leaked during rebuilding, no need to clutter the output with them
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_check_test_img -r all | grep -v '^Repairing cluster.*refcount=1 reference=0'
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echo
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# Check whether the reftable was put where we expected
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rt_offset=$(peek_file_be "$TEST_IMG" 48 8)
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if [[ $rt_offset -eq $data_4k_offset ]]; then
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echo 'OK: Reftable is where we expect it'
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else
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echo "ERROR: Reftable is at $rt_offset, but was expected at $data_4k_offset"
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fi
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echo
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echo '--- Rebuilding refcount structures on block devices ---'
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echo
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# A block device cannot really grow, at least not during qemu-img
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# check. As mentioned in the above cases, rebuilding the refcount
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# structure may lead to new refcount structures being written after
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# the end of the image, and in the past that happened even if there
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# was more than sufficient space in the image. Such post-EOF writes
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# will not work on block devices, so test that the new algorithm
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# avoids it.
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# If we have passwordless sudo and losetup, we can use those to create
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# a block device. Otherwise, we can resort to qemu's FUSE export to
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# create a file that isn't growable, which effectively tests the same
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# thing.
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_cleanup_test_img
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truncate -s $((64 * 1024 * 1024)) "$TEST_IMG"
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if $loopdev; then
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export_mp=$(sudo -n losetup --show -f "$TEST_IMG")
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export_mp_driver=host_device
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sudo -n chmod go+rw "$export_mp"
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else
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# Create non-growable FUSE export that is a bit like an empty
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# block device
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export_mp="$TEST_DIR/fuse-export"
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export_mp_driver=file
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touch "$export_mp"
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$QSD \
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--blockdev file,node-name=export-node,filename="$TEST_IMG" \
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--export fuse,id=fuse-export,node-name=export-node,mountpoint="$export_mp",writable=on,growable=off \
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--pidfile "$TEST_DIR/qsd.pid" \
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--daemonize
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fi
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# Now create a qcow2 image on the device -- unfortunately, qemu-img
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# create force-creates the file, so we have to resort to the
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# blockdev-create job.
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_launch_qemu \
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--blockdev $export_mp_driver,node-name=file,filename="$export_mp"
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_send_qemu_cmd \
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$QEMU_HANDLE \
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'{ "execute": "qmp_capabilities" }' \
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'return'
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# Small cluster size again, so the image needs multiple refblocks
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_send_qemu_cmd \
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$QEMU_HANDLE \
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'{ "execute": "blockdev-create",
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"arguments": {
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"job-id": "create",
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"options": {
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"driver": "qcow2",
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"file": "file",
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"size": '$((64 * 1024 * 1024))',
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"cluster-size": 512
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} } }' \
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'"concluded"'
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_send_qemu_cmd \
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$QEMU_HANDLE \
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'{ "execute": "job-dismiss", "arguments": { "id": "create" } }' \
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'return'
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_send_qemu_cmd \
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$QEMU_HANDLE \
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'{ "execute": "quit" }' \
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'return'
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wait=y _cleanup_qemu
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echo
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# Write some data
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$QEMU_IO -c 'write 0 64k' "$export_mp" | _filter_qemu_io
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# Corrupt the image by saying the image header was not allocated
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rt_offset=$(peek_file_be "$export_mp" 48 8)
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rb_offset=$(peek_file_be "$export_mp" $rt_offset 8)
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poke_file "$export_mp" $rb_offset "\x00\x00"
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# Repairing such a simple case should just work
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# (We used to put the reftable at the end of the image file, which can
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# never work for non-growable devices.)
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echo
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TEST_IMG="$export_mp" _check_test_img -r all \
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| grep -v '^Repairing cluster.*refcount=1 reference=0'
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if $loopdev; then
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sudo -n losetup -d "$export_mp"
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else
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qsd_pid=$(cat "$TEST_DIR/qsd.pid")
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kill -TERM "$qsd_pid"
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# Wait for process to exit (cannot `wait` because the QSD is daemonized)
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while [ -f "$TEST_DIR/qsd.pid" ]; do
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true
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done
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fi
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# success, all done
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echo '*** done'
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rm -f $seq.full
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status=0
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