When resizing an image with qcow2_co_truncate() using the falloc or full preallocation modes the code assumes that both the old and new sizes are cluster-aligned. There are two problems with this: 1) The calculation of how many clusters are involved does not always get the right result. Example: creating a 60KB image and resizing it (with preallocation=full) to 80KB won't allocate the second cluster. 2) No copy-on-write is performed, so in the previous example if there is a backing file then the first 60KB of the first cluster won't be filled with data from the backing file. This patch fixes both issues. Signed-off-by: Alberto Garcia <berto@igalia.com> Message-Id: <20200617140036.20311-1-berto@igalia.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
195 lines
7 KiB
Bash
Executable file
195 lines
7 KiB
Bash
Executable file
#!/usr/bin/env bash
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#
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# Test preallocated growth of qcow2 images
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#
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# Copyright (C) 2017 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=mreitz@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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}
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trap "_cleanup; exit \$status" 0 1 2 3 15
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get_image_size_on_host()
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{
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echo $(($(stat -c '%b * %B' "$TEST_IMG_FILE")))
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}
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# get standard environment and filters
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. ./common.rc
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. ./common.filter
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_supported_fmt qcow2
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_supported_proto file
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if [ -z "$TEST_IMG_FILE" ]; then
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TEST_IMG_FILE=$TEST_IMG
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fi
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# Test whether we are running on a broken XFS version. There is this
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# bug:
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# $ rm -f foo
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# $ touch foo
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# $ block_size=4096 # Your FS's block size
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# $ fallocate -o $((block_size / 2)) -l $block_size foo
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# $ LANG=C xfs_bmap foo | grep hole
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# 1: [8..15]: hole
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#
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# The problem is that the XFS driver rounds down the offset and
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# rounds up the length to the block size, but independently. As
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# such, it only allocates the first block in the example above,
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# even though it should allocate the first two blocks (because our
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# request is to fallocate something that touches both the first
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# two blocks).
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#
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# This means that when you then write to the beginning of the
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# second block, the disk usage of the first two blocks grows.
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#
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# That is precisely what fallocate() promises, though: That when you
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# write to an area that you have fallocated, no new blocks will have
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# to be allocated.
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touch "$TEST_IMG_FILE"
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# Assuming there is no FS with a block size greater than 64k
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fallocate -o 65535 -l 2 "$TEST_IMG_FILE"
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len0=$(get_image_size_on_host)
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# Write to something that in theory we have just fallocated
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# (Thus, the on-disk size should not increase)
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poke_file "$TEST_IMG_FILE" 65536 42
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len1=$(get_image_size_on_host)
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if [ $len1 -gt $len0 ]; then
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_notrun "the test filesystem's fallocate() is broken"
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fi
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rm -f "$TEST_IMG_FILE"
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# Generally, we create some image with or without existing preallocation and
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# then resize it. Then we write some data into the image and verify that its
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# size does not change if we have used preallocation.
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# With a cluster size of 512 B, one L2 table covers 64 * 512 B = 32 kB.
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# One cluster of the L1 table covers 64 * 32 kB = 2 MB.
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# There are multiple cases we want to test:
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# (1) Grow an image without having to allocate a new L2 table.
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# (2) Grow an image, having to allocate a new L2 table.
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# (3) Grow an image, having to grow the L1 table.
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# Therefore, we create an image that is 48 kB below 2 MB. Then:
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# (1) We resize it to 2 MB - 32 kB. (+ 16 kB)
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# (2) We resize it to 2 MB. (+ 48 kB)
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# (3) We resize it to 2 MB + 32 kB. (+ 80 kB)
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# in B
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CREATION_SIZE=$((2 * 1024 * 1024 - 48 * 1024))
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# 512 is the actual test -- but it's good to test 64k as well, just to be sure.
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for cluster_size in 512 64k; do
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# in kB
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for GROWTH_SIZE in 16 48 80; do
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for create_mode in off metadata falloc full; do
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for growth_mode in off metadata falloc full; do
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echo "--- cluster_size=$cluster_size growth_size=$GROWTH_SIZE create_mode=$create_mode growth_mode=$growth_mode ---"
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_make_test_img -o "preallocation=$create_mode,cluster_size=$cluster_size" ${CREATION_SIZE}
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$QEMU_IMG resize -f "$IMGFMT" --preallocation=$growth_mode "$TEST_IMG" +${GROWTH_SIZE}K
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host_size_0=$(get_image_size_on_host)
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file_length_0=$(stat -c '%s' "$TEST_IMG_FILE")
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$QEMU_IO -c "write 0 $CREATION_SIZE" "$TEST_IMG" | _filter_qemu_io
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host_size_1=$(get_image_size_on_host)
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file_length_1=$(stat -c '%s' "$TEST_IMG_FILE")
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$QEMU_IO -c "write $CREATION_SIZE ${GROWTH_SIZE}K" "$TEST_IMG" | _filter_qemu_io
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host_size_2=$(get_image_size_on_host)
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file_length_2=$(stat -c '%s' "$TEST_IMG_FILE")
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# Test creation preallocation: Compare #0 against #1
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if [ $create_mode != off ]; then
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# The image length should not have grown
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if [ $file_length_1 -gt $file_length_0 ]; then
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echo "ERROR (create): Image length has grown from $file_length_0 to $file_length_1"
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fi
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if [ $create_mode != metadata ]; then
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# The host size should not have grown either
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if [ $host_size_1 -gt $host_size_0 ]; then
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echo "ERROR (create): Host size has grown from $host_size_0 to $host_size_1"
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fi
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fi
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fi
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# Test resize preallocation: Compare #2 against #1
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if [ $growth_mode != off ]; then
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# The image length should not have grown
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if [ $file_length_2 -gt $file_length_1 ]; then
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echo "ERROR (grow): Image length has grown from $file_length_1 to $file_length_2"
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fi
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if [ $growth_mode != metadata ]; then
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# The host size should not have grown either
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if [ $host_size_2 -gt $host_size_1 ]; then
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echo "ERROR (grow): Host size has grown from $host_size_1 to $host_size_2"
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fi
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fi
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fi
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echo
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done
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done
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done
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done
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# Test image resizing using preallocation and unaligned offsets
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$QEMU_IMG create -f raw "$TEST_IMG.base" 128k | _filter_img_create
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$QEMU_IO -c 'write -q -P 1 0 128k' -f raw "$TEST_IMG.base"
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for orig_size in 31k 33k; do
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echo "--- Resizing image from $orig_size to 96k ---"
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_make_test_img -F raw -b "$TEST_IMG.base" -o cluster_size=64k "$orig_size"
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$QEMU_IMG resize -f "$IMGFMT" --preallocation=full "$TEST_IMG" 96k
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# The first part of the image should contain data from the backing file
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$QEMU_IO -c "read -q -P 1 0 ${orig_size}" "$TEST_IMG"
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# The resized part of the image should contain zeroes
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$QEMU_IO -c "read -q -P 0 ${orig_size} 63k" "$TEST_IMG"
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# If the image does not have an external data file we can also verify its
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# actual size. The resized image should have 7 clusters:
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# header, L1 table, L2 table, refcount table, refcount block, 2 data clusters
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if ! _get_data_file "$TEST_IMG" > /dev/null; then
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expected_file_length=$((65536 * 7))
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file_length=$(stat -c '%s' "$TEST_IMG_FILE")
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if [ "$file_length" != "$expected_file_length" ]; then
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echo "ERROR: file length $file_length (expected $expected_file_length)"
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fi
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fi
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echo
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done
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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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