btrfs-progs: tests: fix image for 020 which has incorrect super block dev item

[CI FAILURE]
Mark's incoming fsck enhancement on super block device item exposed
the following fs corruption on an existing image dump:

  restoring image keyed_data_ref_with_reloc_leaf.img
  ====== RUN CHECK /home/runner/work/btrfs-progs/btrfs-progs/btrfs check ./keyed_data_ref_with_reloc_leaf.img.restored
  [1/8] checking log skipped (none written)
  [2/8] checking root items
  [3/8] checking extents
  device 1's bytes_used was 55181312 in tree but 59375616 in superblock
  ERROR: errors found in extent allocation tree or chunk allocation
  [4/8] checking free space cache
  [5/8] checking fs roots
  [6/8] checking only csums items (without verifying data)
  [7/8] checking root refs
  [8/8] checking quota groups skipped (not enabled on this FS)
  Opening filesystem to check...
  Checking filesystem on ./keyed_data_ref_with_reloc_leaf.img.restored
  UUID: ca3568a3-d9d8-4901-b4dd-b180a437a07f
  found 1175552 bytes used, error(s) found
  total csum bytes: 512
  total tree bytes: 651264
  total fs tree bytes: 606208
  total extent tree bytes: 16384
  btree space waste bytes: 291631
  file data blocks allocated: 67633152
   referenced 1048576

[CAUSE]
The image has the following device item in the super block:

  dev_item.uuid		5a1c9f96-b581-4fd3-a73a-5cfd789c3c84
  dev_item.fsid		ca3568a3-d9d8-4901-b4dd-b180a437a07f [match]
  dev_item.type		0
  dev_item.total_bytes	67108864
  dev_item.bytes_used	59375616

Meanwhile the tree dump shows the following device item in the chunk
tree:

	item 0 key (DEV_ITEMS DEV_ITEM 1) itemoff 3897 itemsize 98
		devid 1 total_bytes 67108864 bytes_used 55181312
		io_align 4096 io_width 4096 sector_size 4096 type 0

The bytes_used value does not match and triggered the fsck failure.

The root cause of such a mismatch is that, there was a bug in the kernel
that resulted incorrect byte_used number.  The kernel bug was fixed by
commit: ce7213c70c37 ("Btrfs: fix wrong device bytes_used in the super
block").

The image seems to be created by an older kernel without the fix, thus
causing the above mismatch.

[FIX]
Regenerate the image with the latest kernel so that the mismatch won't
happen.

Furthermore for future updates, here is the needed steps to create the
image.

- Modify the kernel btrfs module to commit transaction more frequently
  The idea is to replace the btrfs_end_transaction_throttle() call
  inside the while() loop of relocate_block_group().

  So that every time a tree block is relocated, the fs will be
  committed.

- Use the following script to populate the fs with log-writes
  This requires CONFIG_DM_LOG_WRITES to be enabled.

```

dev_src="/dev/test/scratch1"
dev_log="/dev/test/log"
dev="/dev/mapper/log"
mnt="/mnt/btrfs/"
table="0 $(blockdev --getsz $dev_src) log-writes $dev_src $dev_log"

fail()
{
	echo "!!! FAILED !!!"
	exit 1
}

umount $dev &> /dev/null
umount $mnt &> /dev/null

dmsetup create log --table "$table" || fail
mkfs.btrfs -b 1G -n 4k -f -m single $dev
mount $dev $mnt

xfs_io -f -c "pwrite 0 512k" $mnt/src > /dev/null
sync

for ((i = 0; i < 128; i++)); do
	xfs_io -f -c "reflink $mnt/src $(($i * 4096)) $(($i * 4096)) 4K" $mnt/file1 > /dev/null || fail
done
for ((i = 0; i < 128; i++)); do
	xfs_io -f -c "pwrite 0 2k" $mnt/inline_$i > /dev/null || fail
done
sync
dmsetup message log 0 mark init
btrfs balance start -m $mnt
umount $mnt
dmsetup remove log
```

- Replay the log and run "btrfs dump-tree -t extent" for each fua
  And there will be one with the following contents for the data extent
  item, with mixed keyed and shared backref.

          item 22 key (13631488 EXTENT_ITEM 524288) itemoff 3161 itemsize 108
                refs 180 gen 9 flags DATA
                (178 0xdfb591fbbf5f519) extent data backref root FS_TREE objectid 258 offset 0 count 77
                (178 0xdfb591fa80d95ea) extent data backref root FS_TREE objectid 257 offset 0 count 1
                (184 0x151e000) shared data backref parent 22142976 count 51
                (184 0x512000) shared data backref parent 5316608 count 51

- Take the image of that fs

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

Author: adam900710