On Thu, May 27, 2021 at 11:06:59AM -0700, Darrick J. Wong wrote:

On Wed, May 19, 2021 at 10:13:00PM +1000, Dave Chinner wrote:

quoted

From: Dave Chinner <redacted>

Handle writing of a logvec chain into an iclog that doesn't have
enough space to fit it all. The iclog has already been changed to
WANT_SYNC by xlog_get_iclog_space(), so the entire remaining space
in the iclog is exclusively owned by this logvec chain.

The difference between the single and partial cases is that
we end up with partial iovec writes in the iclog and have to split
a log vec regions across two iclogs. The state handling for this is
currently awful and so we're building up the pieces needed to
handle this more cleanly one at a time.

Signed-off-by: Dave Chinner <redacted>

Egad this diff is hard to read.  Brian's right, the patience diff is
easier to understand and shorter to boot.

That said, I actually understand what the new code does now, so:

Reviewed-by: Darrick J. Wong <djwong@kernel.org>

Thx!

Might be nice to hoist:

	memcpy(ptr, reg->i_addr + reg_offset, rlen);
	xlog_write_adv_cnt(&ptr, len, log_offset, rlen);
	(*record_cnt)++;
	*data_cnt += rlen;

into a helper but it's only four lines so I'm not gonna fuss any
further.

Agreed, there are opportunities for further factoring and
simplification of this code, but I'll leave that for another
patchset rather than risking destabilisation at this late point.

-Dave.
-- 
Dave Chinner
david@fromorbit.com