Re: development APIs for used/free blocks information

Eric Sandeen
2016-04-26T21:33:44Z

On 4/26/16 3:51 PM, Benjamin Wirth wrote:
> Hello,
>
> I was looking for development APIs for XFS. The contents of
> xfsprogs-devel seem to only contain a few IOCTL commands, mostly
> file/inode based operations.
>
> I need to query free/used blocks of an entire XFS filesystem and was
> hoping to find some user-space APIs for this. I have done the same
> task for EXT filesystem which seemed fairly easy as it provided
> simple open/query/close APIs. I know that XFS is a bit different as
> it manages free extents in two B+ trees per AG, but is this free/used
> block/extent information externalized somehow for developers to use?
> Am I not looking in the right place or these functionalities are
> simply not provided to application developers?
>
> Any help/pointers would be greatly appreciated.

It's not exported for application developers, no; it's not
generally something applications need, AFAIK.

You could look at how the freesp_f function works in xfs_db, I suppose.

-Eric