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qcow2: Make preallocate_co() resize the image to the correct size 

This function preallocates metadata structures and then extends the
image to its new size, but that new size calculation is wrong because
it doesn't take into account that the host_offset variable is always
cluster-aligned.

This problem can be reproduced with preallocation=metadata when the
original size is not cluster-aligned but the new size is. In this case
the final image size will be shorter than expected.

   qemu-img create -f qcow2 img.qcow2 31k
   qemu-img resize --preallocation=metadata img.qcow2 128k

Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-Id: <adeb8b059917b141d5f5b3bd2a016262d3052c79.1599833007.git.berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
[mreitz: Mark compat=0.10 unsupported for iotest 125]
Signed-off-by: Max Reitz <mreitz@redhat.com>
master
Alberto Garcia 2020-09-11 16:09:41 +02:00 committed by Max Reitz
parent c1dadda02c
commit 8e958260c5
3 changed files with 53 additions and 20 deletions
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1
block/qcow2.c
View File

@ -3135,6 +3135,7 @@ static int coroutine_fn preallocate_co(BlockDriverState *bs, uint64_t offset,
error_setg_errno(errp, -ret, "Allocating clusters failed");
goto out;
}
host_offset += offset_into_cluster(s, offset);
for (m = meta; m != NULL; m = m->next) {
m->prealloc = true;

44
tests/qemu-iotests/125
View File

@ -43,6 +43,10 @@ get_image_size_on_host()
_supported_fmt qcow2
_supported_proto file
# Growing a file with a backing file (without preallocation=full or
# =falloc) requires zeroing the newly added area, which is impossible
# to do quickly for v2 images, and hence is unsupported.
_unsupported_imgopts 'compat=0.10'
if [ -z "$TEST_IMG_FILE" ]; then
TEST_IMG_FILE=$TEST_IMG
@ -168,24 +172,28 @@ done
$QEMU_IMG create -f raw "$TEST_IMG.base" 128k | _filter_img_create
$QEMU_IO -c 'write -q -P 1 0 128k' -f raw "$TEST_IMG.base"
for orig_size in 31k 33k; do
echo "--- Resizing image from $orig_size to 96k ---"
_make_test_img -F raw -b "$TEST_IMG.base" -o cluster_size=64k "$orig_size"
$QEMU_IMG resize -f "$IMGFMT" --preallocation=full "$TEST_IMG" 96k
# The first part of the image should contain data from the backing file
$QEMU_IO -c "read -q -P 1 0 ${orig_size}" "$TEST_IMG"
# The resized part of the image should contain zeroes
$QEMU_IO -c "read -q -P 0 ${orig_size} 63k" "$TEST_IMG"
# If the image does not have an external data file we can also verify its
# actual size. The resized image should have 7 clusters:
# header, L1 table, L2 table, refcount table, refcount block, 2 data clusters
if ! _get_data_file "$TEST_IMG" > /dev/null; then
expected_file_length=$((65536 * 7))
file_length=$(stat -c '%s' "$TEST_IMG_FILE")
if [ "$file_length" != "$expected_file_length" ]; then
echo "ERROR: file length $file_length (expected $expected_file_length)"
fi
fi
echo
for dst_size in 96k 128k; do
for prealloc in metadata full; do
echo "--- Resizing image from $orig_size to $dst_size (preallocation=$prealloc) ---"
_make_test_img -F raw -b "$TEST_IMG.base" -o cluster_size=64k "$orig_size"
$QEMU_IMG resize -f "$IMGFMT" --preallocation="$prealloc" "$TEST_IMG" "$dst_size"
# The first part of the image should contain data from the backing file
$QEMU_IO -c "read -q -P 1 0 ${orig_size}" "$TEST_IMG"
# The resized part of the image should contain zeroes
$QEMU_IO -c "read -q -P 0 ${orig_size} 63k" "$TEST_IMG"
# If the image does not have an external data file we can also verify its
# actual size. The resized image should have 7 clusters:
# header, L1 table, L2 table, refcount table, refcount block, 2 data clusters
if ! _get_data_file "$TEST_IMG" > /dev/null; then
expected_file_length=$((65536 * 7))
file_length=$(stat -c '%s' "$TEST_IMG_FILE")
if [ "$file_length" != "$expected_file_length" ]; then
echo "ERROR: file length $file_length (expected $expected_file_length)"
fi
fi
echo
done
done
done
# success, all done

28
tests/qemu-iotests/125.out
View File

@ -768,11 +768,35 @@ wrote 81920/81920 bytes at offset 2048000
80 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
Formatting 'TEST_DIR/t.IMGFMT.base', fmt=raw size=131072
--- Resizing image from 31k to 96k ---
--- Resizing image from 31k to 96k (preallocation=metadata) ---
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=31744 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=raw
Image resized.
--- Resizing image from 33k to 96k ---
--- Resizing image from 31k to 96k (preallocation=full) ---
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=31744 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=raw
Image resized.
--- Resizing image from 31k to 128k (preallocation=metadata) ---
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=31744 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=raw
Image resized.
--- Resizing image from 31k to 128k (preallocation=full) ---
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=31744 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=raw
Image resized.
--- Resizing image from 33k to 96k (preallocation=metadata) ---
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33792 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=raw
Image resized.
--- Resizing image from 33k to 96k (preallocation=full) ---
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33792 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=raw
Image resized.
--- Resizing image from 33k to 128k (preallocation=metadata) ---
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33792 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=raw
Image resized.
--- Resizing image from 33k to 128k (preallocation=full) ---
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33792 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=raw
Image resized.