[PATCH v2] common/defrag: skip defrag tests on DAX-enabled filesystems

Online defragmentation is not supported on ext4 DAX-enabled filesystems.
The ext4 defrag ioctl (EXT4_IOC_MOVE_EXT) returns EOPNOTSUPP when used
on DAX files.

Add an ext4-specific check in _require_defrag() to skip tests when DAX
is enabled, avoiding false failures on ext4/301-304, ext4/308, and
generic/018.

XFS defrag works with DAX, so this check is ext4-specific.

Signed-off-by: Disha Goel <[email protected]>
Reviewed-by: Ojaswin Mujoo <[email protected]>
---
Changes in v2:
- Made the check ext4-specific as XFS defrag works with DAX
  (feedback from Darrick)
- Use __scratch_uses_fsdax() instead of grepping MOUNT_OPTIONS
- Removed unnecessary comment as _notrun message is self-explanatory

 common/defrag | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/common/defrag b/common/defrag
index 055d0d0e..f17271cd 100644
--- a/common/defrag
+++ b/common/defrag
@@ -6,6 +6,10 @@
 
 _require_defrag()
 {
+    if [ "$FSTYP" = "ext4" ] && __scratch_uses_fsdax; then
+        _notrun "ext4 online defrag not supported with DAX"
+    fi
+
     case "$FSTYP" in
     xfs)
         # xfs_fsr does preallocates, require "falloc"
-- 
2.45.1