Re: [PATCH 3/9] xfs: don't use xlog_in_core_2_t in struct xlog_in_core

[Christoph Hellwig <hch@lst.de>]

On Tue, Oct 14, 2025 at 02:47:42PM -0700, Darrick J. Wong wrote:
> On Mon, Oct 13, 2025 at 11:42:07AM +0900, Christoph Hellwig wrote:
> > Most accessed to the on-disk log record header are for the original
> > xlog_rec_header.  Make that the main structure, and case for the
> > single remaining place using other union legs.
> > 
> > This prepares for removing xlog_in_core_2_t entirely.
> 
> Er... so xlog_rec_header is the header that gets written out at the
> start of any log buffer?

Yes.

> And if a log record has more than
> XLOG_CYCLE_DATA_SIZE basic blocks (BBs) in it, then it'll have some
> quantity of "extended" headers in the form of a xlog_rec_ext_header
> right after the xlog_rec_header, right?

They are not directly behіnd the current definition of the
xlog_rec_header, but rather at each multiple of 512 bytes past the
start of the xlog_rec_header.

> And both the regular and ext
> headers both have a __be32 array containing the original first four
> bytes of each BB, because each BB has a munged version of the LSN cycle
> stamped into the first four bytes, right?

Yes.

> The previous patch refactored how the cycle_data transformation
> happened, right?

Yes.

> So this patch just gets rid of the strange ic_header #define, and
> updates the code to access ic_data->hic_header directly?  And now that
> we have xlog_cycle_data to abstract the xlog_rec_header ->
> xlog_in_core_2_t casting, this just works fine here.  Right?

Yes.