On Thu, 2013-07-18 at 18:30 -0600, Jens Axboe wrote: > On Thu, Jul 18 2013, Nicholas A. Bellinger wrote: > > On Thu, 2013-07-18 at 13:12 -0600, Mike Christie wrote: > > > On 07/18/2013 12:51 PM, 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().. > > > > > > > > > > blk_mq_make_request is not called from the blk insert/execute paths. > > > blk_mq_make_request takes a bio and tries to merge it with a request and > > > adds it to the queue. It is only called when the make_request_fn is > > > called like when generic_make_request is called. > > > > > > blk_mq_insert_request adds a already formed request to the queue. It is > > > already formed so that is why that path does not bounce bios. The > > > bios/pages should already be added within the drivers restrictions. So > > > for the read_cap path, the call to blk_rq_map_kern in scsi_execute does > > > the blk_queue_bounce call. > > > > > > > <nod>, just noticed the blk_queue_bounce() in blk_rq_map_kern(). > > > > Not sure why this doesn't seem to be doing what it's supposed to for > > libata just yet.. > > How are you make the request from the bio? It'd be pretty trivial to > ensure that it gets bounced properly... blk_mq_execute_rq() assumes a > fully complete request, so it wont bounce anything. > >From what I gather for REQ_TYPE_BLOCK_PC, scsi_execute() -> blk_rq_map_kern() -> blk_rq_append_bio() -> blk_rq_bio_prep() is what does the request setup from the bios returned by bio_[copy,map]_kern() in blk_rq_map_kern() code. blk_queue_bounce() is called immediately after blk_rq_append_bio() here, which AFAICT looks like it's doing the correct thing for scsi-mq.. What is strange here is that libata-scsi.c CDB emulation code is doing the same stuff for both INQUIRY (that seems to be OK) and READ_CAPACITY (that is returning zeros), which makes me think that something else is going on.. Alexander, where you able to re-test using sdev->sdev_mq_reg.queue_depth = 1 in scsi_mq_alloc_queue()..? --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
