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

[Mike Christie <michaelc@cs.wisc.edu>]

Jens Axboe wrote:
> 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.
> 

ok will do.