This patchset add bidi support for block pc requests. With Jens' linked request proposal, there aren't many changes to the block layer, just adding one pointer (next_rq) to the request structure. And there is no changes to the existing block-layer functions. A bidi request uses two request structures (one in request and one out request). The in request is linked and the out request is en-queued. We need some changes to the scsi mid-layer. A new structure, scsi_data_buffer is introduced to hold the in-buffer information. With James' comments via IRC, we should not make the scsi_cmnd structure fatter. So the scsi mid-layer uses req->next_rq->special pointer for a scsi_data_buffer structure. LLDs don't touch the second request (req->next_rq) so it's safe to use req->special. There is no change to the scsi_cmnd structure. The rest of changes include sgtable allocation and deallocation for scsi_data_buffer in the block pc request path. I created a new tree, including this patchset and bsg patches: http://git.kernel.org/?p=linux/kernel/git/tomo/linux-2.6-bidi.git;a=summary I modified and put Boaz's open-iscsi bidi patch in the tree so you can test bidi requests via bsg. I'll put the SMP pass through patches in the tree later. - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
