[PATCH 6.12.y] xfs: flag excessive delalloc rt extents as corruption

[Sasha Levin <sashal@kernel.org>]

From: "Darrick J. Wong" <djwong@kernel.org>

[ Upstream commit 2b47be015a5e54f4a3d62afa636ba593de9b67f6 ]

LOLLM observed that we should not allow repairs to proceed if the count
of delayed-allocation realtime extents exceeds the number of free rt
extents because we can't install negative numbers into the superblock.
It's unclear how we could end up in that state in real life, but let's
at least complain loudly about it if we ever encounter it.

Cc: stable@vger.kernel.org # v6.2
Fixes: e74331d6fa2c21 ("xfs: online checking of the free rt extent count")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Assisted-by: LOLLM # finding obvious bugs
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
[ sashal: removed the xfs_has_zoned() check because zoned filesystem support is absent ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/xfs/scrub/fscounters.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/xfs/scrub/fscounters.c b/fs/xfs/scrub/fscounters.c
index 98634c668b56c..ac7e6329e46e8 100644
--- a/fs/xfs/scrub/fscounters.c
+++ b/fs/xfs/scrub/fscounters.c
@@ -606,6 +606,13 @@ xchk_fscounters(
 			try_again = true;
 	}
 
+	if (fsc->frextents < fsc->frextents_delayed) {
+		if (fsc->frozen)
+			xchk_set_incomplete(sc);
+		else
+			try_again = true;
+	}
+
 	if (!xchk_fscount_within_range(sc, frextents, &mp->m_frextents,
 			fsc->frextents - fsc->frextents_delayed)) {
 		if (fsc->frozen)
-- 
2.53.0