Re: [PATCH 33/43] xfs: enable fsmap reporting for internal RT devices

Christoph Hellwig
2025-02-07T04:55:24Z

On Thu, Feb 06, 2025 at 08:39:01PM -0800, Darrick J. Wong wrote:
> > The bmbt values are all relative to rtstart, the daddr translation is
> > what adds the offset. So if we want to take the offset out of the
> > fsmap reporting, I'll need new helpers to not add it or manually
> > subtract it afterwards. If that's preferred it should be doable, even
> > if the fsmap code keeps confusing me more each time I look at it.
>
> The fmr_physical addresses of the fsmaps reported for the "XFS_DEV_RT"
> device (aka when sb_rtstart > 0) are relative to the start of the data
> device, right?

Yes.

> In a way, that makes it easier to figure out how to set
> up a media scan or a block device to file translation, because the
> fmr_physical number you feed in and get out of fsmap always matches the
> device LBA.

Yes.