[PATCH] xfs: add a test that zoned file systems with rump RTG can't be mounted

[Christoph Hellwig <hch@lst.de>]

Garbage collection assumes all zones contain the full amount of blocks.
Mkfs already ensures this happens, but the kernel mount code did not
verify this.  Instead such a file system would eventually fail scrub.

Add a test to verify the new superblock verifier check.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 tests/xfs/651     | 27 +++++++++++++++++++++++++++
 tests/xfs/651.out |  2 ++
 2 files changed, 29 insertions(+)
 create mode 100755 tests/xfs/651
 create mode 100644 tests/xfs/651.out

diff --git a/tests/xfs/651 b/tests/xfs/651
new file mode 100755
index 000000000000..3aef7a1d016f
--- /dev/null
+++ b/tests/xfs/651
@@ -0,0 +1,27 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2025 Christoph Hellwig.
+#
+# FS QA Test No. 651
+#
+# Test that the sb verifier rejects zoned file system with rump RTGs.
+#
+. ./common/preamble
+_begin_fstest auto quick zone
+
+. ./common/zoned
+
+_require_scratch
+
+_scratch_mkfs > /dev/null 2>&1
+blocks=$(_scratch_xfs_db -c 'sb 0' -c 'print rblocks' | awk '{print $3}')
+blocks=$((blocks - 4096))
+_scratch_xfs_db -x -c 'sb 0' -c "write -d rblocks $blocks" > /dev/null 2>&1
+_scratch_xfs_db -x -c 'sb 0' -c "write -d rextents $blocks" > /dev/null 2>&1
+_try_scratch_mount || _notrun "Can't mount rump RTG file system"
+
+# for non-zoned file systems this can succeed
+_require_xfs_scratch_zoned
+
+status=0
+exit
diff --git a/tests/xfs/651.out b/tests/xfs/651.out
new file mode 100644
index 000000000000..62617d172811
--- /dev/null
+++ b/tests/xfs/651.out
@@ -0,0 +1,2 @@
+QA output created by 651
+Can't mount rump RTG file system
-- 
2.47.3