Re: [PATCH v2 2/3] block: Add badblock management for gendisks

["Verma, Vishal L" <vishal.l.verma@intel.com>]

On Fri, 2015-12-04 at 15:33 -0800, James Bottomley wrote:
[...]
> >  static void register_disk(struct gendisk *disk)
> >  {
> >  	struct device *ddev = disk_to_dev(disk);
> > @@ -609,6 +624,7 @@ void add_disk(struct gendisk *disk)
> >  	disk->first_minor = MINOR(devt);
> >  
> >  	disk_alloc_events(disk);
> > +	disk_alloc_badblocks(disk);
> 
> Why unconditionally do this?  No-one currently uses the interface, but
> every disk will now pay the price of an additional structure plus a
> page
> for no benefit.  You should probably either export the initializer for
> those who want to use it or, perhaps even better, make it lazily
> allocated the first time anyone tries to set a bad block.
> 
> If you come up with a really good reason for allocating it
> unconditionally, then it should probably be an embedded structure in
> the gendisk.
> 
Agreed - I'll fix for v3.

I'm considering an embedded structure in gendisk (same as md) (why is
this preferred to pointer chasing, especially when this wastes more
space?), and a new exported initializer that is used by anyone who wants
to use gendisk's badblocks.

	-Vishal