[dm-devel] convert dm-thin to use dm-bufio

[Mikulas Patocka]

On Fri, 19 Aug 2011, Mike Snitzer wrote:

> On Thu, Aug 18 2011 at  6:31pm -0400,
> Mikulas Patocka <mpatocka at redhat.com> wrote:
> 
> > > This all sounds good; get the locking interface in and I'll switch to
> > > bufio straight away.
> > > 
> > > - Joe
> > 
> > I uploaded bufio-based block manager at 
> > http://people.redhat.com/mpatocka/patches/kernel/dm-thinp-bufio/. It 
> > supports locks, but it defines new functions down_write_non_owner and 
> > up_write_non_owner.
> 
> dm-bufio.patch:
> drivers/md/Kconfig needs a more comprehensive description for DM_BUFIO's
> help.

There is intentionally no description. If there is no description, this 
option won't appear in "make menuconfig" menu.

dm-bufio is selected automatically when some module that needs it is 
configured. There is no need to select dm-bufio manually.

> dm-thinp-bufio.patch:
> 1)
> This drivers/md/persistent-data/dm-block-manager.h change avoids lots of
> block manager interface churn:
> 
> -struct dm_block;
> +#define dm_block		dm_buffer
> +#define dm_block_manager	dm_bufio_client
> 
> But I think it'd be best, in the long run, to have a follow-on patch
> that does away with the aliases and just use the bufio structs
> throughout the code.  Anyway, don't need to worry about this now.  But
> what you've done is hack that should probably be cleaned up.

This way, it's easy to swap the original block manager and dm-bufio.

If I changed the names throughout the whole dm-thinp code, it would 
conflict with any changes Joe may do.

Mikulas