iotests: Add test for failing qemu-img commit

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20170616135847.17726-1-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

tests/qemu-iotests/020

@@ -110,6 +110,33 @@ for offset in $TEST_OFFSETS; do
     io_zero readv $(( offset + 64 * 1024 + 65536 * 4 )) 65536 65536 1
 done
 _check_test_img
+_cleanup
+TEST_IMG=$TEST_IMG_SAVE
+
+echo
+echo 'Testing failing commit'
+echo
+
+# Create an image with a null backing file to which committing will fail (with
+# ENOSPC so we can distinguish the result from some generic EIO which may be
+# generated anywhere in the block layer)
+_make_test_img -b "json:{'driver': 'raw',
+                         'file': {
+                             'driver': 'blkdebug',
+                             'inject-error': [{
+                                 'event': 'write_aio',
+                                 'errno': 28,
+                                 'once': true
+                             }],
+                             'image': {
+                                 'driver': 'null-co'
+                             }}}"
+
+# Just write anything so committing will not be a no-op
+$QEMU_IO -c 'writev 0 64k' "$TEST_IMG" | _filter_qemu_io
+
+$QEMU_IMG commit "$TEST_IMG"
+_cleanup_test_img
 
 # success, all done
 echo "*** done"

tests/qemu-iotests/020.out

@@ -1075,4 +1075,21 @@ read 65536/65536 bytes at offset 4295098368
 read 65536/65536 bytes at offset 4295294976
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 No errors were found on the image.
+
+Testing failing commit
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824 backing_file=json:{'driver': 'raw',,
+                         'file': {
+                             'driver': 'blkdebug',,
+                             'inject-error': [{
+                                 'event': 'write_aio',,
+                                 'errno': 28,,
+                                 'once': true
+                             }],,
+                             'image': {
+                                 'driver': 'null-co'
+                             }}}
+wrote 65536/65536 bytes at offset 0
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-img: Block job failed: No space left on device
 *** done