Re: [PATCH 06/10] xfs: regularize iclog space accounting in xlog_write_partial

[Christoph Hellwig <hch@lst.de>]

On Tue, Nov 04, 2025 at 03:53:09PM -0800, Darrick J. Wong wrote:
> On Thu, Oct 30, 2025 at 03:49:16PM +0100, Christoph Hellwig wrote:
> > When xlog_write_partial splits a log region over multiple iclogs, it
> > has to include the continuation ophder in the length requested for the
> > new iclog.  Currently is simply adds that to the request, which makes
> > the accounting of the used space below look slightly different from the
> > other users of iclog space that decrement it.  To prepare for more code
> > sharing, adding the ophdr size to the len variable before the call to
> > xlog_write_get_more_iclog_space and then decrement it later.
> > 
> > This changes the contents of len when xlog_write_get_more_iclog_space
> > returns an error, but as nothing looks at len in that case the
> > difference doesn't matter.
> 
> Ooops, sorry I missed this patch. :(
> 
> It makes sense to me that we have to account for the continuation when
> asking for a fresh iclog, but now I have a question.  In "xfs: improve
> the calling convention for the xlog_write helpers", the len pointer
> becomes xlog_write_data::bytes_left.  In the context of this patch, I
> guess that means "len" is the amount of log data that we still have to
> write to the log, correct?

Yes.