Commit 4096974e authored by Eric Blake's avatar Eric Blake Committed by Kevin Wolf
Browse files

qcow2: fix image corruption on commit with persistent bitmap 



If an image contains persistent bitmaps, we cannot use the
fast path of bdrv_make_empty() to clear the image during
qemu-img commit, because that will lose the clusters related
to the bitmaps.

Also leave a comment in qcow2_read_extensions to remind future
feature additions to think about fast-path removal, since we
just barely fixed the same bug for LUKS encryption.

It's a pain that qemu-img has not yet been taught to manipulate,
or even at a very minimum display, information about persistent
bitmaps; instead, we have to use QMP commands.  It's also a
pain that only qeury-block and x-debug-block-dirty-bitmap-sha256
will allow bitmap introspection; but the former requires the
node to be hooked to a block device, and the latter is experimental.

Signed-off-by: default avatarEric Blake <eblake@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 3590cd0f

block/qcow2.c

+10 −7
Original line number Diff line number Diff line
@@ -376,6 +376,8 @@ static int qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset, 


        default:

            /* unknown magic - save it in case we need to rewrite the header */

            /* If you add a new feature, make sure to also update the fast

             * path of qcow2_make_empty() to deal with it. */

            {

                Qcow2UnknownHeaderExtension *uext;
@@ -3600,15 +3602,16 @@ static int qcow2_make_empty(BlockDriverState *bs) 


    l1_clusters = DIV_ROUND_UP(s->l1_size, s->cluster_size / sizeof(uint64_t));



    if (s->qcow_version >= 3 && !s->snapshots &&

    if (s->qcow_version >= 3 && !s->snapshots && !s->nb_bitmaps &&

        3 + l1_clusters <= s->refcount_block_size &&

        s->crypt_method_header != QCOW_CRYPT_LUKS) {

        /* The following function only works for qcow2 v3 images (it requires

         * the dirty flag) and only as long as there are no snapshots (because

         * it completely empties the image). Furthermore, the L1 table and three

         * additional clusters (image header, refcount table, one refcount

         * block) have to fit inside one refcount block. It cannot be used

         * for LUKS (yet) as it throws away the LUKS header cluster(s) */

        /* The following function only works for qcow2 v3 images (it

         * requires the dirty flag) and only as long as there are no

         * features that reserve extra clusters (such as snapshots,

         * LUKS header, or persistent bitmaps), because it completely

         * empties the image.  Furthermore, the L1 table and three

         * additional clusters (image header, refcount table, one

         * refcount block) have to fit inside one refcount block. */

        return make_completely_empty(bs);

    }

tests/qemu-iotests/176

+48 −7
Original line number Diff line number Diff line
@@ -3,10 +3,11 @@ 
# Commit changes into backing chains and empty the top image if the

# backing image is not explicitly specified.

#

# Variant of 097, which includes snapshots to test different codepath

# in qcow2

# Variant of 097, which includes snapshots and persistent bitmaps, to

# tickle the slow codepath in qcow2. See also 198, for another feature

# that tickles the slow codepath.

#

# Copyright (C) 2014 Red Hat, Inc.

# Copyright (C) 2014, 2017 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
@@ -43,11 +44,18 @@ trap "_cleanup; exit \$status" 0 1 2 3 15 
. ./common.filter

. ./common.pattern



# Any format supporting backing files and bdrv_make_empty

# This test is specific to qcow2

_supported_fmt qcow2

_supported_proto file

_supported_os Linux



function run_qemu()

{

    $QEMU -nographic -qmp stdio -serial none "$@" 2>&1 \

	| _filter_testdir | _filter_qmp | _filter_qemu

}



for reason in snapshot bitmap; do



# Four passes:

#  0: Two-layer backing chain, commit to upper backing file (implicitly)
@@ -66,14 +74,29 @@ _supported_os Linux 
for i in 0 1 2 3; do



echo

echo "=== Test pass $i ==="

echo "=== Test pass $reason.$i ==="

echo



len=$((2100 * 1024 * 1024 + 512)) # larger than 2G, and not cluster aligned

TEST_IMG="$TEST_IMG.base" _make_test_img $len

TEST_IMG="$TEST_IMG.itmd" _make_test_img -b "$TEST_IMG.base" $len

_make_test_img -b "$TEST_IMG.itmd" $len

$QEMU_IMG snapshot -c snap "$TEST_IMG"

# Update the top image to use a feature that is incompatible with fast path

case $reason in

    snapshot) $QEMU_IMG snapshot -c snap "$TEST_IMG" ;;

    bitmap)

	run_qemu <<EOF

{ "execute": "qmp_capabilities" }

{ "execute": "blockdev-add",

  "arguments": { "driver": "qcow2", "node-name": "drive0",

     "file": { "driver": "file", "filename": "$TEST_IMG" } } }

{ "execute": "block-dirty-bitmap-add",

  "arguments": { "node": "drive0", "name": "bitmap0",

     "persistent": true, "autoload": true } }

{ "execute": "quit" }

EOF

	;;

esac



$QEMU_IO -c "write -P 1 0x7ffd0000 192k" "$TEST_IMG.base" | _filter_qemu_io

$QEMU_IO -c "write -P 2 0x7ffe0000 128k" "$TEST_IMG.itmd" | _filter_qemu_io
@@ -122,8 +145,26 @@ $QEMU_IMG map "$TEST_IMG.base" | _filter_qemu_img_map 
$QEMU_IMG map "$TEST_IMG.itmd" | _filter_qemu_img_map

$QEMU_IMG map "$TEST_IMG" | _filter_qemu_img_map



done

# Check that the reason for slow path is still present, as appropriate

case $reason in

    snapshot)

	$QEMU_IMG snapshot -l "$TEST_IMG" |

	    sed 's/^\(.\{20\}\).*/\1/; s/ *$//' ;;

    bitmap)

	run_qemu <<EOF

{ "execute": "qmp_capabilities" }

{ "execute": "blockdev-add",

  "arguments": { "driver": "qcow2", "node-name": "drive0",

     "file": { "driver": "file", "filename": "$TEST_IMG" } } }

{ "execute": "x-debug-block-dirty-bitmap-sha256",

  "arguments": { "node": "drive0", "name": "bitmap0" } }

{ "execute": "quit" }

EOF

	;;

esac



done

done



# success, all done

echo "*** done"

tests/qemu-iotests/176.out

+212 −4
Original line number Diff line number Diff line 
QA output created by 176



=== Test pass 0 ===

=== Test pass snapshot.0 ===



Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=2202010112

Formatting 'TEST_DIR/t.IMGFMT.itmd', fmt=IMGFMT size=2202010112 backing_file=TEST_DIR/t.IMGFMT.base
@@ -36,8 +36,11 @@ Offset Length File 
0x7ffd0000      0x10000         TEST_DIR/t.IMGFMT.base

0x7ffe0000      0x20000         TEST_DIR/t.IMGFMT.itmd

0x83400000      0x200           TEST_DIR/t.IMGFMT.itmd

Snapshot list:

ID        TAG

1         snap



=== Test pass 1 ===

=== Test pass snapshot.1 ===



Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=2202010112

Formatting 'TEST_DIR/t.IMGFMT.itmd', fmt=IMGFMT size=2202010112 backing_file=TEST_DIR/t.IMGFMT.base
@@ -74,8 +77,11 @@ Offset Length File 
0x7ffe0000      0x10000         TEST_DIR/t.IMGFMT.itmd

0x7fff0000      0x10000         TEST_DIR/t.IMGFMT

0x83400000      0x200           TEST_DIR/t.IMGFMT

Snapshot list:

ID        TAG

1         snap



=== Test pass 2 ===

=== Test pass snapshot.2 ===



Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=2202010112

Formatting 'TEST_DIR/t.IMGFMT.itmd', fmt=IMGFMT size=2202010112 backing_file=TEST_DIR/t.IMGFMT.base
@@ -112,8 +118,11 @@ Offset Length File 
0x7ffe0000      0x10000         TEST_DIR/t.IMGFMT.itmd

0x7fff0000      0x10000         TEST_DIR/t.IMGFMT

0x83400000      0x200           TEST_DIR/t.IMGFMT

Snapshot list:

ID        TAG

1         snap



=== Test pass 3 ===

=== Test pass snapshot.3 ===



Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=2202010112

Formatting 'TEST_DIR/t.IMGFMT.itmd', fmt=IMGFMT size=2202010112 backing_file=TEST_DIR/t.IMGFMT.base
@@ -147,4 +156,203 @@ Offset Length File 
0x7ffe0000      0x10000         TEST_DIR/t.IMGFMT.itmd

0x7fff0000      0x10000         TEST_DIR/t.IMGFMT

0x83400000      0x200           TEST_DIR/t.IMGFMT

Snapshot list:

ID        TAG

1         snap



=== Test pass bitmap.0 ===



Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=2202010112

Formatting 'TEST_DIR/t.IMGFMT.itmd', fmt=IMGFMT size=2202010112 backing_file=TEST_DIR/t.IMGFMT.base

Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=2202010112 backing_file=TEST_DIR/t.IMGFMT.itmd

QMP_VERSION

{"return": {}}

{"return": {}}

{"return": {}}

{"return": {}}

{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "SHUTDOWN", "data": {"guest": false}}

wrote 196608/196608 bytes at offset 2147287040

192 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

wrote 131072/131072 bytes at offset 2147352576

128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

wrote 65536/65536 bytes at offset 2147418112

64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

wrote 512/512 bytes at offset 2202009600

512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

Image committed.

read 196608/196608 bytes at offset 2147287040

192 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 512/512 bytes at offset 2202009600

512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 65536/65536 bytes at offset 2147287040

64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 65536/65536 bytes at offset 2147352576

64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 65536/65536 bytes at offset 2147418112

64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 512/512 bytes at offset 2202009600

512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

Offset          Length          File

0x7ffd0000      0x30000         TEST_DIR/t.IMGFMT.base

Offset          Length          File

0x7ffd0000      0x10000         TEST_DIR/t.IMGFMT.base

0x7ffe0000      0x20000         TEST_DIR/t.IMGFMT.itmd

0x83400000      0x200           TEST_DIR/t.IMGFMT.itmd

Offset          Length          File

0x7ffd0000      0x10000         TEST_DIR/t.IMGFMT.base

0x7ffe0000      0x20000         TEST_DIR/t.IMGFMT.itmd

0x83400000      0x200           TEST_DIR/t.IMGFMT.itmd

QMP_VERSION

{"return": {}}

{"return": {}}

{"return": {"sha256": "e12600978d86b5a453861ae5c17d275204673fef3874b7c3c5433c6153d84706"}}

{"return": {}}

{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "SHUTDOWN", "data": {"guest": false}}



=== Test pass bitmap.1 ===



Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=2202010112

Formatting 'TEST_DIR/t.IMGFMT.itmd', fmt=IMGFMT size=2202010112 backing_file=TEST_DIR/t.IMGFMT.base

Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=2202010112 backing_file=TEST_DIR/t.IMGFMT.itmd

QMP_VERSION

{"return": {}}

{"return": {}}

{"return": {}}

{"return": {}}

{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "SHUTDOWN", "data": {"guest": false}}

wrote 196608/196608 bytes at offset 2147287040

192 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

wrote 131072/131072 bytes at offset 2147352576

128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

wrote 65536/65536 bytes at offset 2147418112

64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

wrote 512/512 bytes at offset 2202009600

512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

Image committed.

read 196608/196608 bytes at offset 2147287040

192 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 512/512 bytes at offset 2202009600

512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 65536/65536 bytes at offset 2147287040

64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 65536/65536 bytes at offset 2147352576

64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 65536/65536 bytes at offset 2147418112

64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 512/512 bytes at offset 2202009600

512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

Offset          Length          File

0x7ffd0000      0x30000         TEST_DIR/t.IMGFMT.base

Offset          Length          File

0x7ffd0000      0x10000         TEST_DIR/t.IMGFMT.base

0x7ffe0000      0x20000         TEST_DIR/t.IMGFMT.itmd

0x83400000      0x200           TEST_DIR/t.IMGFMT.itmd

Offset          Length          File

0x7ffd0000      0x10000         TEST_DIR/t.IMGFMT.base

0x7ffe0000      0x10000         TEST_DIR/t.IMGFMT.itmd

0x7fff0000      0x10000         TEST_DIR/t.IMGFMT

0x83400000      0x200           TEST_DIR/t.IMGFMT

QMP_VERSION

{"return": {}}

{"return": {}}

{"return": {"sha256": "e12600978d86b5a453861ae5c17d275204673fef3874b7c3c5433c6153d84706"}}

{"return": {}}

{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "SHUTDOWN", "data": {"guest": false}}



=== Test pass bitmap.2 ===



Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=2202010112

Formatting 'TEST_DIR/t.IMGFMT.itmd', fmt=IMGFMT size=2202010112 backing_file=TEST_DIR/t.IMGFMT.base

Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=2202010112 backing_file=TEST_DIR/t.IMGFMT.itmd

QMP_VERSION

{"return": {}}

{"return": {}}

{"return": {}}

{"return": {}}

{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "SHUTDOWN", "data": {"guest": false}}

wrote 196608/196608 bytes at offset 2147287040

192 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

wrote 131072/131072 bytes at offset 2147352576

128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

wrote 65536/65536 bytes at offset 2147418112

64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

wrote 512/512 bytes at offset 2202009600

512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

Image committed.

read 196608/196608 bytes at offset 2147287040

192 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 512/512 bytes at offset 2202009600

512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 65536/65536 bytes at offset 2147287040

64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 65536/65536 bytes at offset 2147352576

64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 65536/65536 bytes at offset 2147418112

64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 512/512 bytes at offset 2202009600

512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

Offset          Length          File

0x7ffd0000      0x30000         TEST_DIR/t.IMGFMT.base

Offset          Length          File

0x7ffd0000      0x10000         TEST_DIR/t.IMGFMT.base

0x7ffe0000      0x20000         TEST_DIR/t.IMGFMT.itmd

0x83400000      0x200           TEST_DIR/t.IMGFMT.itmd

Offset          Length          File

0x7ffd0000      0x10000         TEST_DIR/t.IMGFMT.base

0x7ffe0000      0x10000         TEST_DIR/t.IMGFMT.itmd

0x7fff0000      0x10000         TEST_DIR/t.IMGFMT

0x83400000      0x200           TEST_DIR/t.IMGFMT

QMP_VERSION

{"return": {}}

{"return": {}}

{"return": {"sha256": "e12600978d86b5a453861ae5c17d275204673fef3874b7c3c5433c6153d84706"}}

{"return": {}}

{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "SHUTDOWN", "data": {"guest": false}}



=== Test pass bitmap.3 ===



Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=2202010112

Formatting 'TEST_DIR/t.IMGFMT.itmd', fmt=IMGFMT size=2202010112 backing_file=TEST_DIR/t.IMGFMT.base

Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=2202010112 backing_file=TEST_DIR/t.IMGFMT.itmd

QMP_VERSION

{"return": {}}

{"return": {}}

{"return": {}}

{"return": {}}

{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "SHUTDOWN", "data": {"guest": false}}

wrote 196608/196608 bytes at offset 2147287040

192 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

wrote 131072/131072 bytes at offset 2147352576

128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

wrote 65536/65536 bytes at offset 2147418112

64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

wrote 512/512 bytes at offset 2202009600

512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

Image committed.

read 65536/65536 bytes at offset 2147287040

64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 65536/65536 bytes at offset 2147352576

64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 65536/65536 bytes at offset 2147418112

64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

read 512/512 bytes at offset 2202009600

512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

Offset          Length          File

0x7ffd0000      0x30000         TEST_DIR/t.IMGFMT.base

0x83400000      0x200           TEST_DIR/t.IMGFMT.base

Offset          Length          File

0x7ffd0000      0x10000         TEST_DIR/t.IMGFMT.base

0x7ffe0000      0x20000         TEST_DIR/t.IMGFMT.itmd

0x83400000      0x200           TEST_DIR/t.IMGFMT.base

Offset          Length          File

0x7ffd0000      0x10000         TEST_DIR/t.IMGFMT.base

0x7ffe0000      0x10000         TEST_DIR/t.IMGFMT.itmd

0x7fff0000      0x10000         TEST_DIR/t.IMGFMT

0x83400000      0x200           TEST_DIR/t.IMGFMT

QMP_VERSION

{"return": {}}

{"return": {}}

{"return": {"sha256": "e12600978d86b5a453861ae5c17d275204673fef3874b7c3c5433c6153d84706"}}

{"return": {}}

{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "SHUTDOWN", "data": {"guest": false}}

*** done