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

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

[Disha Goel]

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 [ "$FSTYP" = "ext4" ] && __scratch_uses_fsdax; then
+        _notrun "ext4 online defrag not supported with DAX"
+    fi
+
     case "$FSTYP" in
     xfs)
         # xfs_fsr does preallocates, require "falloc"
-- 
2.45.1

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

[Darrick J. Wong]

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

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

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

[Disha Goel]

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