[PATCH 8/9] xfs/166: fix golden output failures when multipage folios enabled

["Darrick J. Wong" <djwong@kernel.org>]

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

Beginning with 5.18, some filesystems support creating large folios for
the page cache.  A system with 64k pages can create 256k folios, which
means that with the old file size of 1M, the last half of the file is
completely converted from unwritten to written by page_mkwrite.  The
test encodes a translated version of the xfs_bmap output in the golden
output, which means that the test now fails on 64k pages.  Fixing the
64k page case by increasing the file size to 2MB broke fsdax because
fsdax uses 2MB PMDs, hence 12MB.

Increase the size to prevent this from happening.  This may require
further revision if folios get larger or fsdax starts supporting PMDs
that are larger than 2MB.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 tests/xfs/166 |   19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)


diff --git a/tests/xfs/166 b/tests/xfs/166
index 42379961..d45dc5e8 100755
--- a/tests/xfs/166
+++ b/tests/xfs/166
@@ -16,12 +16,12 @@ _begin_fstest rw metadata auto quick
 # the others are unwritten.
 _filter_blocks()
 {
-	$AWK_PROG '
+	$AWK_PROG -v file_size=$FILE_SIZE '
 /^ +[0-9]/ {
 	if (!written_size) {
 		written_size = $6
-		unwritten1 = ((1048576/512) / 2) - written_size
-		unwritten2 = ((1048576/512) / 2) - 2 * written_size
+		unwritten1 = ((file_size/512) / 2) - written_size
+		unwritten2 = ((file_size/512) / 2) - 2 * written_size
 	}
 
 	# is the extent unwritten?
@@ -58,7 +58,18 @@ _scratch_mount
 
 TEST_FILE=$SCRATCH_MNT/test_file
 TEST_PROG=$here/src/unwritten_mmap
-FILE_SIZE=1048576
+
+# Beginning with 5.18, some filesystems support creating large folios for the
+# page cache.  A system with 64k pages can create 256k folios, which means
+# that with the old file size of 1M, the last half of the file is completely
+# converted from unwritten to written by page_mkwrite.  The test will fail on
+# the golden output when this happens, so increase the size from the original
+# 1MB file size to at least (6 * 256k == 1.5MB) prevent this from happening.
+#
+# However, increasing the file size to around 2MB causes regressions when fsdax
+# is enabled because fsdax will try to use PMD entries for the mappings.  Hence
+# we need to set the file size to (6 * 2MB == 12MB) to cover all cases.
+FILE_SIZE=$((12 * 1048576))
 
 rm -f $TEST_FILE
 $TEST_PROG $FILE_SIZE $TEST_FILE