Re: [PATCH RFC 0/4] use scatter lists for all block pc requests and simplify hw handlers

[Douglas Gilbert <dougg@torque.net>]

James Bottomley wrote:
> On Tue, 2005-06-07 at 20:07 +0200, Jens Axboe wrote:
> 
>>I've slowly been doing the same thing in other places in the kernel and
>>this bit has been talked about between James and I for at least a year
>>or two.
> 
> 
> Yes, it's long been a dream of mine to eliminate at least struct
> scsi_request and just use block struct request for everything in the
> SCSI layer.
> 
> The most pleasing aspect of this will be getting rid of the dma mapping
> duplications in st and sg.

James,
A "char_uld" library that st, sg, ch and the proposed OSD
ULDs could tap into, would cut the duplication. As you can
see, Kai and I have shared implementations in this area but
had no mechanism for sharing the actual code.

An idea I had was to flag what mechanism inserted a
command onto a request queue and when a blk_pc_request()
follows a blk_pc_request() then use FIFO order for
the second one.

Doug Gilbert