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

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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>
This commit is contained in:
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
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@ -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;

12
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
@ -168,9 +172,11 @@ 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 ---"
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=full "$TEST_IMG" 96k
$QEMU_IMG resize -f "$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
@ -187,6 +193,8 @@ for orig_size in 31k 33k; do
fi
echo
done
done
done
# success, all done
echo '*** 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.