Re: [Qemu-devel] [PATCH 2/2] iotests: Add test for checking large image files

[Eric Blake <eblake@redhat.com>]

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On 09/08/2015 02:09 PM, Max Reitz wrote:
> Add a test for checking a qcow2 file with a multiple of 2^32 clusters.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  tests/qemu-iotests/138     | 73 ++++++++++++++++++++++++++++++++++++++++++++++
>  tests/qemu-iotests/138.out |  9 ++++++
>  tests/qemu-iotests/group   |  1 +
>  3 files changed, 83 insertions(+)
>  create mode 100755 tests/qemu-iotests/138
>  create mode 100644 tests/qemu-iotests/138.out
> 

> +# Put the data cluster at a multiple of 2 TB, resulting in the image apparently
> +# having a multiple of 2^32 clusters
> +# (To be more specific: It is at 32 PB)
> +poke_file "$TEST_IMG" 2048 "\x80\x80\x00\x00\x00\x00\x00\x00"
> +
> +# An offset of 32 PB results in qemu-img check having to allocate an in-memory
> +# refcount table of 128 TB (16 bit refcounts, 512 byte clusters).
> +# This should be generally too much for any system and thus fail.
> +# What this test is checking is that the qcow2 driver actually tries to allocate
> +# such a large amount of memory (and is consequently aborting) instead of having
> +# truncated the cluster count somewhere (which would result in much less memory
> +# being allocated and then a segfault occuring).

s/occuring/occurring/

With the typo fixed,
Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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