block: Guard against NULL bs->drv
We currently do not guard everywhere against a NULL bs->drv where we
should be doing so. Most of the places fixed here just do not care
about that case at all.
Some care implicitly, e.g. through a prior function call to
bdrv_getlength() which would always fail for an ejected BDS. Add an
assert there to make it more obvious.
Other places seem to care, but do so insufficiently: Freeing clusters in
a qcow2 image is an error-free operation, but it may leave the image in
an unusable state anyway. Giving qcow2_free_clusters() an error code is
not really viable, it is much easier to note that bs->drv may be NULL
even after a successful driver call. This concerns bdrv_co_flush(), and
the way the check is added to bdrv_co_pdiscard() (in every iteration
instead of only once).
Finally, some places employ at least an assert(bs->drv); somewhere, that
may be reasonable (such as in the reopen code), but in
bdrv_has_zero_init(), it is definitely not. Returning 0 there in case
of an ejected BDS saves us much headache instead.
Reported-by: R. Nageswara Sastry <nasastry@in.ibm.com>
Buglink: https://bugs.launchpad.net/qemu/+bug/1728660
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20171110203111.7666-4-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
diff --git a/tests/qemu-iotests/060 b/tests/qemu-iotests/060
index 49bc89d..44141f6 100755
--- a/tests/qemu-iotests/060
+++ b/tests/qemu-iotests/060
@@ -337,6 +337,28 @@
# Can't repair this yet (TODO: We can just deallocate the cluster)
+echo
+echo '=== Discarding with an unaligned refblock ==='
+echo
+
+_make_test_img 64M
+
+$QEMU_IO -c "write 0 128k" "$TEST_IMG" | _filter_qemu_io
+# Make our refblock unaligned
+poke_file "$TEST_IMG" "$(($rt_offset))" "\x00\x00\x00\x00\x00\x00\x2a\x00"
+# Now try to discard something that will be submitted as two requests
+# (main part + tail)
+$QEMU_IO -c "discard 0 65537" "$TEST_IMG"
+
+echo '--- Repairing ---'
+# Fails the first repair because the corruption prevents the check
+# function from double-checking
+# (Using -q for the first invocation, because otherwise the
+# double-check error message appears above the summary for some
+# reason -- so let's just hide the summary)
+_check_test_img -q -r all
+_check_test_img -r all
+
# success, all done
echo "*** done"
rm -f $seq.full
