Proposals to change the way all drivers work with SCSI commands

[James Bottomley <James.Bottomley@SteelEye.com>]

Right at the moment, we're planning to clean up the way SCSI drivers
process commands.  The proposals are essentially:

     1. Get rid of the now unnecessary map_single path (every command is
        either zero transfer or scatter/gather)
     2. use accessors to manipulate the SG lists (mainly so that we can
        alter the implementation without affecting the drivers)

It strikes me that in all of this, we could also consider doing the DMA
mapping inside the mid layer (instead of in every driver).  This is
essentially what libata is already doing ... leading to confusion in
SCSI drivers that use libata for SATA.

So what do people think about this?

James