[PATCH v2] qcow2: Fix preallocation on images with unaligned sizes

Alberto Garcia posted 1 patch 3 years, 10 months ago
Test asan failed
Test docker-mingw@fedora passed
Test FreeBSD passed
Test docker-quick@centos7 passed
Test checkpatch passed
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20200617140036.20311-1-berto@igalia.com
Maintainers: Max Reitz <mreitz@redhat.com>, Kevin Wolf <kwolf@redhat.com>
block/qcow2.c              | 17 ++++++++++++++---
tests/qemu-iotests/125     | 24 ++++++++++++++++++++++++
tests/qemu-iotests/125.out |  9 +++++++++
3 files changed, 47 insertions(+), 3 deletions(-)
[PATCH v2] qcow2: Fix preallocation on images with unaligned sizes
Posted by Alberto Garcia 3 years, 10 months ago
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>
---
v2: iotests: don't check the image size if data_file is set [Max]

 block/qcow2.c              | 17 ++++++++++++++---
 tests/qemu-iotests/125     | 24 ++++++++++++++++++++++++
 tests/qemu-iotests/125.out |  9 +++++++++
 3 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index 0cd2e6757e..e20590c3b7 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -4239,8 +4239,8 @@ static int coroutine_fn qcow2_co_truncate(BlockDriverState *bs, int64_t offset,
             old_file_size = ROUND_UP(old_file_size, s->cluster_size);
         }
 
-        nb_new_data_clusters = DIV_ROUND_UP(offset - old_length,
-                                            s->cluster_size);
+        nb_new_data_clusters = (ROUND_UP(offset, s->cluster_size) -
+            start_of_cluster(s, old_length)) >> s->cluster_bits;
 
         /* This is an overestimation; we will not actually allocate space for
          * these in the file but just make sure the new refcount structures are
@@ -4317,10 +4317,21 @@ static int coroutine_fn qcow2_co_truncate(BlockDriverState *bs, int64_t offset,
             int64_t nb_clusters = MIN(
                 nb_new_data_clusters,
                 s->l2_slice_size - offset_to_l2_slice_index(s, guest_offset));
-            QCowL2Meta allocation = {
+            unsigned cow_start_length = offset_into_cluster(s, guest_offset);
+            QCowL2Meta allocation;
+            guest_offset = start_of_cluster(s, guest_offset);
+            allocation = (QCowL2Meta) {
                 .offset       = guest_offset,
                 .alloc_offset = host_offset,
                 .nb_clusters  = nb_clusters,
+                .cow_start    = {
+                    .offset       = 0,
+                    .nb_bytes     = cow_start_length,
+                },
+                .cow_end      = {
+                    .offset       = nb_clusters << s->cluster_bits,
+                    .nb_bytes     = 0,
+                },
             };
             qemu_co_queue_init(&allocation.dependent_requests);
 
diff --git a/tests/qemu-iotests/125 b/tests/qemu-iotests/125
index d510984045..7cb1c19730 100755
--- a/tests/qemu-iotests/125
+++ b/tests/qemu-iotests/125
@@ -164,6 +164,30 @@ for GROWTH_SIZE in 16 48 80; do
 done
 done
 
+# Test image resizing using preallocation and unaligned offsets
+$QEMU_IMG create -f raw "$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
+done
+
 # success, all done
 echo '*** done'
 rm -f $seq.full
diff --git a/tests/qemu-iotests/125.out b/tests/qemu-iotests/125.out
index 596905f533..7f76f7af20 100644
--- a/tests/qemu-iotests/125.out
+++ b/tests/qemu-iotests/125.out
@@ -767,4 +767,13 @@ wrote 2048000/2048000 bytes at offset 0
 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 ---
+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 ---
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33792 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=raw
+Image resized.
+
 *** done
-- 
2.20.1


Re: [PATCH v2] qcow2: Fix preallocation on images with unaligned sizes
Posted by no-reply@patchew.org 3 years, 10 months ago
Patchew URL: https://patchew.org/QEMU/20200617140036.20311-1-berto@igalia.com/



Hi,

This series failed the asan build test. Please find the testing commands and
their output below. If you have Docker installed, you can probably reproduce it
locally.

=== TEST SCRIPT BEGIN ===
#!/bin/bash
export ARCH=x86_64
make docker-image-fedora V=1 NETWORK=1
time make docker-test-debug@fedora TARGET_LIST=x86_64-softmmu J=14 NETWORK=1
=== TEST SCRIPT END ===

  GEN     docs/interop/qemu-qmp-ref.txt
  GEN     docs/interop/qemu-qmp-ref.7
  CC      qga/commands.o
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
  CC      qga/guest-agent-command-state.o
  CC      qga/main.o
  CC      qga/commands-posix.o
---
  GEN     docs/interop/qemu-ga-ref.html
  GEN     docs/interop/qemu-ga-ref.txt
  GEN     docs/interop/qemu-ga-ref.7
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
  AS      pc-bios/optionrom/multiboot.o
  AS      pc-bios/optionrom/linuxboot.o
  CC      pc-bios/optionrom/linuxboot_dma.o
---
  SIGN    pc-bios/optionrom/kvmvapic.bin
  SIGN    pc-bios/optionrom/multiboot.bin
  SIGN    pc-bios/optionrom/linuxboot.bin
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
  LINK    ivshmem-server
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
  LINK    qemu-nbd
  BUILD   pc-bios/optionrom/linuxboot_dma.img
  BUILD   pc-bios/optionrom/pvh.img
---
  BUILD   pc-bios/optionrom/pvh.raw
  SIGN    pc-bios/optionrom/linuxboot_dma.bin
  SIGN    pc-bios/optionrom/pvh.bin
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
  LINK    qemu-storage-daemon
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
  LINK    qemu-img
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
  LINK    qemu-io
  LINK    qemu-edid
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
  LINK    fsdev/virtfs-proxy-helper
  LINK    scsi/qemu-pr-helper
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
  LINK    qemu-bridge-helper
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
  LINK    virtiofsd
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
  LINK    vhost-user-input
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
  LINK    qemu-ga
/usr/bin/ld: /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors_vfork.S.o): warning: common of `__interception::real_vfork' overridden by definition from /usr/lib64/clang/10.0.0/lib/linux/libclang_rt.asan-x86_64.a(asan_interceptors.cpp.o)
  GEN     x86_64-softmmu/hmp-commands.h
  GEN     x86_64-softmmu/config-target.h
  GEN     x86_64-softmmu/hmp-commands-info.h
---
  CC      x86_64-softmmu/dump/dump.o
  CC      x86_64-softmmu/dump/win_dump.o
  CC      x86_64-softmmu/hw/9pfs/virtio-9p-device.o
/tmp/qemu-test/src/fpu/softfloat.c:3365:13: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
    absZ &= ~ ( ( ( roundBits ^ 0x40 ) == 0 ) & roundNearestEven );
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            !
/tmp/qemu-test/src/fpu/softfloat.c:3423:18: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
        absZ0 &= ~ ( ( (uint64_t) ( absZ1<<1 ) == 0 ) & roundNearestEven );
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                 !
/tmp/qemu-test/src/fpu/softfloat.c:3483:18: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
        absZ0 &= ~(((uint64_t)(absZ1<<1) == 0) & roundNearestEven);
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                 !
/tmp/qemu-test/src/fpu/softfloat.c:3606:13: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
    zSig &= ~ ( ( ( roundBits ^ 0x40 ) == 0 ) & roundNearestEven );
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            !
/tmp/qemu-test/src/fpu/softfloat.c:3760:13: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
    zSig &= ~ ( ( ( roundBits ^ 0x200 ) == 0 ) & roundNearestEven );
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            !
/tmp/qemu-test/src/fpu/softfloat.c:3987:21: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
                    ~ ( ( (uint64_t) ( zSig1<<1 ) == 0 ) & roundNearestEven );
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                    !
/tmp/qemu-test/src/fpu/softfloat.c:4003:22: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
            zSig0 &= ~ ( ( (uint64_t) ( zSig1<<1 ) == 0 ) & roundNearestEven );
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                     !
/tmp/qemu-test/src/fpu/softfloat.c:4273:18: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
        zSig1 &= ~ ( ( zSig2 + zSig2 == 0 ) & roundNearestEven );
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                 !
8 errors generated.
make[1]: *** [/tmp/qemu-test/src/rules.mak:69: fpu/softfloat.o] Error 1
make[1]: *** Waiting for unfinished jobs....
/tmp/qemu-test/src/migration/ram.c:919:45: error: implicit conversion from 'unsigned long' to 'double' changes value from 18446744073709551615 to 18446744073709551616 [-Werror,-Wimplicit-int-float-conversion]
            xbzrle_counters.encoding_rate = UINT64_MAX;
                                          ~ ^~~~~~~~~~
/usr/include/stdint.h:130:23: note: expanded from macro 'UINT64_MAX'
---
18446744073709551615UL
^~~~~~~~~~~~~~~~~~~~~~
1 error generated.
make[1]: *** [/tmp/qemu-test/src/rules.mak:69: migration/ram.o] Error 1
make: *** [Makefile:527: x86_64-softmmu/all] Error 2
Traceback (most recent call last):
  File "./tests/docker/docker.py", line 669, in <module>
    sys.exit(main())
---
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['sudo', '-n', 'docker', 'run', '--label', 'com.qemu.instance.uuid=4b33ee20f63a4affba4da2d49a64ab50', '-u', '1003', '--security-opt', 'seccomp=unconfined', '--rm', '-e', 'TARGET_LIST=x86_64-softmmu', '-e', 'EXTRA_CONFIGURE_OPTS=', '-e', 'V=', '-e', 'J=14', '-e', 'DEBUG=', '-e', 'SHOW_ENV=', '-e', 'CCACHE_DIR=/var/tmp/ccache', '-v', '/home/patchew2/.cache/qemu-docker-ccache:/var/tmp/ccache:z', '-v', '/var/tmp/patchew-tester-tmp-reb2wndp/src/docker-src.2020-06-17-10.23.04.9345:/var/tmp/qemu:z,ro', 'qemu:fedora', '/var/tmp/qemu/run', 'test-debug']' returned non-zero exit status 2.
filter=--filter=label=com.qemu.instance.uuid=4b33ee20f63a4affba4da2d49a64ab50
make[1]: *** [docker-run] Error 1
make[1]: Leaving directory `/var/tmp/patchew-tester-tmp-reb2wndp/src'
make: *** [docker-run-test-debug@fedora] Error 2

real    4m36.131s
user    0m7.959s


The full log is available at
http://patchew.org/logs/20200617140036.20311-1-berto@igalia.com/testing.asan/?type=message.
---
Email generated automatically by Patchew [https://patchew.org/].
Please send your feedback to patchew-devel@redhat.com
Re: [PATCH v2] qcow2: Fix preallocation on images with unaligned sizes
Posted by Eric Blake 3 years, 10 months ago
On 6/17/20 9:00 AM, Alberto Garcia wrote:
> 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>
> ---
> v2: iotests: don't check the image size if data_file is set [Max]
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org


Re: [PATCH v2] qcow2: Fix preallocation on images with unaligned sizes
Posted by Alberto Garcia 3 years, 10 months ago
ping

On Wed 17 Jun 2020 04:00:36 PM CEST, Alberto Garcia wrote:
> 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>

Re: [PATCH v2] qcow2: Fix preallocation on images with unaligned sizes
Posted by Max Reitz 3 years, 10 months ago
On 17.06.20 16:00, Alberto Garcia wrote:
> 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>
> ---
> v2: iotests: don't check the image size if data_file is set [Max]
> 
>  block/qcow2.c              | 17 ++++++++++++++---
>  tests/qemu-iotests/125     | 24 ++++++++++++++++++++++++
>  tests/qemu-iotests/125.out |  9 +++++++++
>  3 files changed, 47 insertions(+), 3 deletions(-)

Thanks, applied to my block branch:

https://git.xanclic.moe/XanClic/qemu/commits/branch/block