Re: [PATCH 1/7] iscsi-target: Fix iscsit_alloc_buffs() breakage with offset_in_page

[Andy Grover <agrover@redhat.com>]

On 06/04/2011 07:21 AM, Christoph Hellwig wrote:
> On Fri, Jun 03, 2011 at 06:18:12PM -0700, Nicholas A. Bellinger wrote:
>> From: Nicholas Bellinger <nab@linux-iscsi.org>
>>
>> This patch changes iscsit_alloc_buffs() w/ SCF_SCSI_CONTROL_NONSG_IO_CDB
>> to take into account the offset_in_page(), and also handles the case
>> where length and PAGE_SIZE are identical, and require nents to be incremented.
>>
>> It also moves iscsit_allocate_iovecs() for the SCSI payload case until
>> after transport_generic_map_mem_to_cmd() has been called because the
>> iovec allocation depends upon cmd->se_cmd.t_tasks_se_num having been
>> set by the return of transport_map_sg_to_mem() done in RX thread context.
> 
> I'd rather just remove the SCF_SCSI_CONTROL_NONSG_IO_CDB side of the
> code path, and always allocate one page per S/G list item.  That simplifies
> the code, and fixes the issues with non-aligned kmallocs.

I thought about doing that but didn't quite have the guts.

It *would* simplify things a lot, though. Offsets of offsets are no fun.
+1 from me. Express everything in pages and scatterlists.

-- Andy