Re: [PATCH 3/6] scsi tgt: add partial mappings support to bio_map_user

[Jens Axboe <axboe@suse.de>]

On Thu, Feb 16 2006, Mike Christie wrote:
> Subject: [PATCH] block layer: add partial mappings support to bio_map_user
> 
> For target mode we could end up with the case where we get very large
> request from the initiator. The request could be so large that we
> cannot transfer all the data in one operation. For example the
> HBA's segment or max_sector limits might limit us to a 1 MB transfer.
> To send a 5 MB command then we need to transfer the command chunk by chunk.
> 
> To do this, tgt core will map in as much data as possible into a bio,
> send this off, then when that transfer is completed we send off another
> request/bio. To be able to pack as much data into a bio as possible
> we need bio_map_user to support partially mapped bios. The attached patch
> just adds a new argument to the those functions and if set will not
> return a failure if the bio is partially mapped.

Drop the partial flag and just always allow it, fixing up the few
in-kernel users we have.

-- 
Jens Axboe