[PATCH] fstests: btrfs/138: add requirement for datacsum

[FALSE ALERT]
If one has specified "-o nodatasum" as mount options, the test case
btrfs/138 will fail with the following error:

 MOUNT_OPTIONS -- -o nodatasum /dev/mapper/test-scratch1 /mnt/scratch

 btrfs/138    34s ... - output mismatch (see /home/adam/xfstests/results//btrfs/138.out.bad)
    --- tests/btrfs/138.out	2022-05-11 11:25:30.743333331 +0930
    +++ /home/adam/xfstests/results//btrfs/138.out.bad	2026-06-08 09:04:30.627143086 +0930
    @@ -1,2 +1,5 @@
     QA output created by 138
    +ERROR: failed to set compression for /mnt/scratch/zlib: Invalid argument
    +ERROR: failed to set compression for /mnt/scratch/lzo: Invalid argument
    +ERROR: failed to set compression for /mnt/scratch/zstd: Invalid argument
     Silence is golden
    ...

[CAUSE]
Btrfs compression requires both datacow and datasum, thus nodatasum
mount option will reject compression completely, causing the above
failures.

[FIX]
Add _require_btrfs_no_nodatasum for the test case, so that for nodatasum
mount option the test case can be properly skipped other than causing
false failure.

Signed-off-by: Qu Wenruo <[email protected]>
---
 tests/btrfs/138 | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/btrfs/138 b/tests/btrfs/138
index 17bbe28e..57ab1bd3 100755
--- a/tests/btrfs/138
+++ b/tests/btrfs/138
@@ -15,6 +15,7 @@ _begin_fstest auto compress
 _require_scratch
 _require_btrfs_command property
 _require_btrfs_no_nodatacow
+_require_btrfs_no_nodatasum
 
 algos=($(_btrfs_compression_algos))
 
-- 
2.51.2