On 04/26/2018 07:10 AM, Alberto Garcia wrote:
On Thu 26 Apr 2018 04:51:28 AM CEST, Eric Blake wrote:
If you have a capable file system (tmpfs is good, ext4 not so much;
run ./check with TEST_DIR pointing to a good location so as not
to skip the test), it's actually possible to create a qcow2 file
that expands to a sparse 512T image with just over 38M of content.
The test is not the world's fastest (qemu crawling through 256M
bits of refcount table to find the next cluster to allocate takes
several seconds, as does qemu-img check reporting millions of
leaked clusters); but it DOES catch the problem that the previous
patch just fixed where writing a compressed cluster to a full
image ended up overwriting the wrong cluster.

Suggested-by: Max Reitz <mre...@redhat.com>
Signed-off-by: Eric Blake <ebl...@redhat.com>

Nice test :-)

Reviewed-by: Alberto Garcia <be...@igalia.com>

214 is already in the tree in the meantime; this will need a rebase to pick the next available test number (220 might be claimed, so 222?)

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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