On Wed, 2008-03-05 at 01:42 +0900, Tejun Heo wrote: > Tejun Heo wrote: > > Tejun Heo wrote: > >> FUJITA Tomonori wrote: > >>>> Aiee... device going down after timing out on READ_DISC_INFO. That's > >>>> gruesome. Can you please try the other patches? > >>> Tejun, I thought that libata needs a fix for sum(sg) != rq->data_len. No? > >> The extra_len you added to qc->nbytes should be it. The only other > >> place to pay attention is the ATAPI transfer chunk size and your patch > >> seems to get it right. > >> > >>> Now Jens' git tree should work with all the non libata stuff, ide, > >>> firewire, bsg, etc. But I'm not sure about libata. > >> With the second patch, all others should be fine no matter what. I'll > >> go check libata part again. > > > > I can reproduce the problem here and it's very weird. I'll report back > > when I know more. > > Okay, I got it. Heh, it turns out SCSI and/or block layer is not > ready for rq->data_len != sum(sg). When adjusted command completes, > SCSI midlayer completes the command with rq->data_len for PC commands > which eventually ends up in __end_that_request_first(). As there are > extra sg area left after completing rq->data_len, blk layer says so to > SCSI layer and SCSI layer retries the command only with the appended > area. > > The following patch gets the writing going. I really think it's a > serious mistake to break rq->data_len == sum(sg). If we break > rq->data_len == requested size, the worst bugs are giving wrong size > when issuing commands to application layer of devices which is > relatively easy to spot and not all that command anyway. Breaking > rq->data_len == sum(sg), bugs will be in internal mechanics, DMA > engine programming and transport layer. Oh well... > > diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c > index fecba05..32439ac 100644 > --- a/drivers/scsi/scsi.c > +++ b/drivers/scsi/scsi.c > @@ -757,7 +757,7 @@ void scsi_finish_command(struct scsi_cmnd *cmd) > "Notifying upper driver of completion " > "(result %x)\n", cmd->result)); > > - good_bytes = scsi_bufflen(cmd); > + good_bytes = scsi_bufflen(cmd) + cmd->request->data_len; This doesn't look right. scsi_bufflen(cmd) is req->data_len for PC commands ... did you mean to add extra_len here? James -- 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
