btrfs-progs: tests: add image for btrfstune bgt conversion

The image has a half converted fs, unfortunately btrfs-image cannot
properly maintain the CHANGING_BG_TREE super block flags, thus we have
to go raw image.

The half-converted image has the following two block groups in the
extent tree:

	item 0 key (1048576 BLOCK_GROUP_ITEM 4194304) itemoff 3971 itemsize 24
		block group used 4096 chunk_objectid 256 flags SYSTEM|single

	item 2 key (5242880 BLOCK_GROUP_ITEM 8388608) itemoff 3914 itemsize 24
		block group used 401408 chunk_objectid 256 flags METADATA|single

And the following block groups in the block group tree:

	item 0 key (13631488 BLOCK_GROUP_ITEM 8388608) itemoff 3971 itemsize 24
		block group used 8388608 chunk_objectid 256 flags DATA|single
	item 1 key (22020096 BLOCK_GROUP_ITEM 67108864) itemoff 3947 itemsize 24
		block group used 66584576 chunk_objectid 256 flags DATA|single
	item 2 key (89128960 BLOCK_GROUP_ITEM 67108864) itemoff 3923 itemsize 24
		block group used 59244544 chunk_objectid 256 flags DATA|single

This in layout in fact is pretty good, as if by somehow the block group
items loading bug skipped any block group, it will cause the fs to have
no SYSTEM or METADATA space type.

Unpatched btrfstune have a very high chance to cause the following
error:

  ERROR: unable to find block group for profile 0x4
  Unable to find block group for 0
  Unable to find block group for 0
  Unable to find block group for 0
  Unable to find block group for 0
  Unable to find block group for 0
  Unable to find block group for 0
  ERROR: failed to commit transaction for the new chunk: No space left on device
  ERROR: failed to start transaction: No space left on device
  ERROR: failed to convert the filesystem to block group tree feature
  ERROR: btrfstune failed
  extent buffer leak: start 5308416 len 4096

Signed-off-by: Qu Wenruo <[email protected]>
Signed-off-by: David Sterba <[email protected]>

Author: adam900710

tests/misc-tests/069-btrfstune-resume-bgt/half-converted-bgt.raw.xz

@@ -0,0 +1,15 @@
+#!/bin/bash
+# To check if btrfstune can handle half converted fs.
+#
+# Due to a bug in the block group items loading code, old block groups items
+# in the old extent tree can be skipped, thus causing resume failure.
+
+source "$TEST_TOP/common" || exit
+
+check_prereq btrfs
+
+check_image() {
+	run_check "$TOP/btrfstune" --convert-to-block-group-tree "$1"
+}
+
+check_all_images