Re: [PATCH 1/2] iotests: Improve and rename test 291 to qemu-img-bitmap

[Vladimir Sementsov-Ogievskiy]

09.07.2021 16:16, Eric Blake wrote:
> On Fri, Jul 09, 2021 at 09:33:50AM +0300, Vladimir Sementsov-Ogievskiy wrote:
> > > +++ b/tests/qemu-iotests/tests/qemu-img-bitmaps
>
> > > +echo
> > > +echo "=== Check handling of inconsistent bitmap ==="
> > > +echo
> > > +
> > > +$QEMU_IO -c abort "$TEST_IMG" 2>/dev/null
> > > +$QEMU_IMG bitmap --add "$TEST_IMG" b4
> > > +$QEMU_IMG bitmap --remove "$TEST_IMG" b1
> > > +_img_info --format-specific | _filter_irrelevant_img_info
> > > +$QEMU_IMG convert --bitmaps -O qcow2 "$TEST_IMG" "$TEST_IMG.copy"
> >
> > Worth then removing remaining inconsistent bitmaps and try again?
> >
> > I think you should now remove $TEST_IMG.copy in _cleanup
>
> $TEST_IMG.copy isn't created on failure (or if it is, that in itself
> is a problem we should be avoiding),

Seems that's the case:
./build/qemu-img create -f qcow2 x 1M
./build/qemu-img bitmap --add x b1
./build/qemu-io x
qemu-io> abort
Aborted (core dumped)
 ./build/qemu-img info x
image: x
file format: qcow2
virtual size: 1 MiB (1048576 bytes)
disk size: 204 KiB
cluster_size: 65536
Format specific information:
    compat: 1.1
    compression type: zlib
    lazy refcounts: false
    bitmaps:
        [0]:
            flags:
                [0]: in-use
                [1]: auto
            name: b1
            granularity: 65536
    refcount bits: 16
    corrupt: false
    extended l2: false


ls y
ls: cannot access 'y': No such file or directory
./build/qemu-img convert --bitmaps -O qcow2 x y
qemu-img: Failed to populate bitmap b1: Bitmap 'b1' is inconsistent and cannot 
be used
Try block-dirty-bitmap-remove to delete this bitmap from disk[root@kvm master]#
# ls y
y
./build/qemu-img info y
image: y
file format: qcow2
virtual size: 1 MiB (1048576 bytes)
disk size: 204 KiB
cluster_size: 65536
Format specific information:
    compat: 1.1
    compression type: zlib
    lazy refcounts: false
    bitmaps:
        [0]:
            flags:
            name: b1
            granularity: 65536
    refcount bits: 16
    corrupt: false
    extended l2: false


WOW! It even contains the bitmap not marked in-use. That's a real bug.

> so as written, there was nothing
> that should have needed cleaning up until patch 2.  But your idea
> (here and in patch 2) of demonstrating manual cleanup for recovery (in
> addition to the goal of patch 2 of skipping broken bitmaps in the
> first place) is reasonable, so I'll incorporate that into v2.


--
Best regards,
Vladimir