Re: [PATCH v1] xfs: Fix rgcount/rgsize value reported in XFS_IOC_FSGEOMETRY ioctl

["Nirjhar Roy (IBM)" <nirjhar.roy.lists@gmail.com>]

On 12/8/25 23:10, Darrick J. Wong wrote:
> On Mon, Dec 08, 2025 at 08:46:11PM +0530, Nirjhar Roy (IBM) wrote:
>> With mkfs.xfs -m dir=0 i.e, with XFS_SB_FEAT_INCOMPAT_METADIR
>> disabled, number of realtime groups should be reported as 1 and
>> the size of it should be equal to total number of realtime
>> extents since this the entire realtime filesystem has only 1
>> realtime group.
> No.  This (pre-metadir realtime having one group encompassing the entire
> rt volume) is an implementation detail, not a property of the filesystem
> geometry.
>
> Or put another way: a metadir rt filesystem with one rtgroup that covers
> the entire rt device is different from a pre-metadir rt filesystem.
> xfs_info should present that distinction to userspace, particularly
> since xfs_scrub cares about that difference.

Okay, got it. A quick question:

A metadir rt filesystem will have 1 bitmap/summary file per rt AG, isn't 
it? If yes, then shouldn't functions like xfs_rtx_to_rbmblock(mp, 
xfs_rtxnum_t        rtx) return offset of the corresponding bitmap file 
of the rt AG where rtx belongs? Right now, looking at the definition of 
xfs_rtx_to_rbmblock() it looks like it calculates the offset as if there 
is only 1 global bitmap file?

--NR

>
> --D
>
>> Signed-off-by: Nirjhar Roy (IBM) <nirjhar.roy.lists@gmail.com>
>> ---
>>   fs/xfs/libxfs/xfs_sb.c | 8 +++-----
>>   1 file changed, 3 insertions(+), 5 deletions(-)
>>
>> diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
>> index cdd16dd805d7..989553e7ec02 100644
>> --- a/fs/xfs/libxfs/xfs_sb.c
>> +++ b/fs/xfs/libxfs/xfs_sb.c
>> @@ -875,7 +875,7 @@ __xfs_sb_from_disk(
>>   	} else {
>>   		to->sb_metadirino = NULLFSINO;
>>   		to->sb_rgcount = 1;
>> -		to->sb_rgextents = 0;
>> +		to->sb_rgextents = to->sb_rextents;
>>   	}
>>   
>>   	if (to->sb_features_incompat & XFS_SB_FEAT_INCOMPAT_ZONED) {
>> @@ -1586,10 +1586,8 @@ xfs_fs_geometry(
>>   
>>   	geo->version = XFS_FSOP_GEOM_VERSION_V5;
>>   
>> -	if (xfs_has_rtgroups(mp)) {
>> -		geo->rgcount = sbp->sb_rgcount;
>> -		geo->rgextents = sbp->sb_rgextents;
>> -	}
>> +	geo->rgcount = sbp->sb_rgcount;
>> +	geo->rgextents = sbp->sb_rgextents;
>>   	if (xfs_has_zoned(mp)) {
>>   		geo->rtstart = sbp->sb_rtstart;
>>   		geo->rtreserved = sbp->sb_rtreserved;
>> -- 
>> 2.43.5
>>
>>
-- 
Nirjhar Roy
Linux Kernel Developer
IBM, Bangalore