[lvm-devel] [PATCH 2 of 10] LVM: make log_area a list

[Alasdair G Kergon]

On Thu, Oct 08, 2009 at 04:18:36PM -0500, Jon Brassow wrote:
> -	struct alloced_area log_area;	/* Extent used for log */
> +	struct dm_list log_areas;	/* Extents used for logs */
>  	struct dm_list alloced_areas[0];	/* Lists of areas in each stripe */

Rather than storing the log areas differently (in a list) from the other areas
(in an array), I'd prefer them all to be stored the same way.

I.e. In a simple contiguous 2-leg mirror plus mirrored log, you'd get
  leg1 as first item on alloced_areas[0] list,
  leg2 as first item on alloced_areas[1] list,
  log leg1 as first item on log_areas list, 
  log leg2 as second item on log_areas list.

I'd prefer to see:
  leg1 as first item on alloced_areas[0] list,
  leg2 as first item on alloced_areas[1] list,
  log leg1 as first item on log_areas[0] list, 
  log leg2 as first item on log_areas[1] list.
and of course log_areas[0] can be the same as alloced_areas[2].

This should be both simpler (logs are less of a special case and 
like any other area may include more than 1 segment) and more general
(we're asking to allocate several parallel areas, with different lengths
but sorted largest first and with different allocation constraints
applying to some of them).

Alasdair