[PATCH] xfs/191: fix xattr leaf block emptying on 64k blocksized fses

[Anthony Iliopoulos <ailiop@suse.com>]

This test is failing on filesystems with 64k blocksize since the leaf
hdr.firstused field is 16 bit and as such trying to reset it to $dbsize
overflows and is rejected by xfs_db. The leaf is never properly resetted
and the discrepancy is picked up by xfs_repair, thus failing the test.

Fix it by setting it to XFS_ATTR3_LEAF_NULLOFF (0) as this is the proper
on-disk value to indicate an empty leaf on 64k blocksized fses.

Signed-off-by: Anthony Iliopoulos <ailiop@suse.com>
---
 tests/xfs/191 | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/tests/xfs/191 b/tests/xfs/191
index 4f0a9b9eeef5..8dd875fcd28b 100755
--- a/tests/xfs/191
+++ b/tests/xfs/191
@@ -78,10 +78,20 @@ make_empty_leaf() {
 
 	base=$(_scratch_xfs_get_metadata_field "hdr.freemap[0].base" "inode $inum" "ablock 0")
 
+	# 64k dbsize is a special case since it overflows the 16 bit firstused
+	# field and it needs to be set to the special XFS_ATTR3_LEAF_NULLOFF (0)
+	# value to indicate a null leaf. For more details see kernel commit:
+	# e87021a2bc10 ("xfs: use larger in-core attr firstused field and detect overflow").
+	if [ $dbsize -eq 65536 ]; then
+		firstused=0;
+	else
+		firstused=$dbsize;
+	fi
+
 	_scratch_xfs_db -x -c "inode $inum" -c "ablock 0" \
 		-c "write -d hdr.count 0" \
 		-c "write -d hdr.usedbytes 0" \
-		-c "write -d hdr.firstused $dbsize" \
+		-c "write -d hdr.firstused $firstused" \
 		-c "write -d hdr.freemap[0].size $((dbsize - base))" \
 		-c print >> $seqres.full
 }
-- 
2.35.3