On Thu, 2013-07-18 at 11:51 -0700, Nicholas A. Bellinger wrote: > On Wed, 2013-07-17 at 18:19 +0200, Alexander Gordeev wrote: > > On Tue, Jul 16, 2013 at 02:38:03PM -0700, Nicholas A. Bellinger wrote: > > > [ 7.927818] scsi_execute(): Calling blk_mq_free_request >>> > > > [ 7.927826] scsi 0:0:0:0: Direct-Access ATA ST9500530NS CC03 PQ: 0 ANSI: 5 > > > > > > OK, so INQUIRY response payload is looking as expected here. > > > > Yep. It is not on the top of my head, but I remember something like INQUIRYs > > are emulated and thus do not have payload. > > > > > [ 7.927960] sd 0:0:0:0: [sda] Sector size 0 reported, assuming 512. > > > [ 7.927964] sd 0:0:0:0: [sda] 1 512-byte logical blocks: (512 B/512 B) > > > [ 7.927965] sd 0:0:0:0: [sda] 0-byte physical blocks > > > > > > Strange.. READ_CAPACITY appears to be returning a payload as zeros..? > > > > Yep. Because blk_execute_rq() does not put the proper callback and data do > > not get copied from sg's to bounce buffer. That is why I tried to use > > blk_mq_execute_rq() instead. Once I do that, data start getting read and > > booting stops elsewhere. > > Mmmmmm. > > The call to blk_queue_bounce() exists within blk_mq_make_request(), but > AFAICT this should still be getting invoked regardless of if the struct > request is dispatched into blk-mq via the modified blk_execute_rq() -> > blk_execute_rq_nowait() -> blk_mq_insert_request() codepath, or directly > via blk_mq_execute_rq().. > > Jens..? > Actually sorry, your right. A call to blk_mq_insert_request() for REQ_TYPE_BLOCK_PC will not invoke blk_queue_bounce() located near the top of blk_mq_execute_rq(), which means that only REQ_TYPE_FS is currently using bounce buffers, if required. Need to think a bit more about what to do here for REQ_TYPE_BLOCK_PC bounce buffer special case with blk_execute_rq(), but I'm thinking that blk_mq_execute_rq() should really not be used here.. Jens..? --nab -- 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
