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

[Disha Goel <disgoel@linux.ibm.com>]

On 04/06/26 8:24 pm, Darrick J. Wong wrote:
> On Thu, Jun 04, 2026 at 05:53:05PM +0530, Disha Goel wrote:
>> 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 <disgoel@linux.ibm.com>
>> Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
>> ---
>> 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
> 
> Shouldn't this be:
> 
> 	ext4)
> 		__scratch_uses_fsdax && _notrun "..."
> 		;;
> 
> in the case statement below?
> 
> --D

Yes, that makes more sense. Keeping the ext4-specific check inside the
ext4 case is cleaner and more consistent with the existing structure.

I'll send v3 with this change.

> 
>> +        _notrun "ext4 online defrag not supported with DAX"
>> +    fi
>> +
>>       case "$FSTYP" in
>>       xfs)
>>           # xfs_fsr does preallocates, require "falloc"
>> -- 
>> 2.45.1
>>

-- 
Regards,
Disha