a3e1505dae
The qcow2_make_empty() function is reached during 'qemu-img commit', in order to clear out ALL clusters of an image. However, if the image cannot use the fast code path (true if the image is format 0.10, or if the image contains a snapshot), the cluster size is larger than 512, and the image is larger than 2G in size, then our choice of sector_step causes problems. Since it is not cluster aligned, but qcow2_discard_clusters() silently ignores an unaligned head or tail, we are leaving clusters allocated. Enhance the testsuite to expose the flaw, and patch the problem by ensuring our step size is aligned. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
=== This is the QEMU I/O test suite === * Intro This package contains a simple test suite for the I/O layer of qemu. It does not require a guest, but only the qemu, qemu-img and qemu-io binaries. This does limit it to exercise the low-level I/O path only but no actual block drivers like ide, scsi or virtio. * Usage Just run ./check to run all tests for the raw image format, or ./check -qcow2 to test the qcow2 image format. The output of ./check -h explains additional options to test further image formats or I/O methods. * Feedback and patches Please send improvements to the test suite, general feedback or just reports of failing tests cases to qemu-devel@nongnu.org with a CC: to qemu-block@nongnu.org.