On Wed, 2013-08-21 at 08:53 -0700, Christoph Hellwig wrote: > On Wed, Aug 21, 2013 at 07:38:21AM -0700, Roland Dreier wrote: > > I don't understand this. In fact the whole patch series looks quite > > confused. COMPARE AND WRITE is a normal Data-Out command, with no > > requirement for special bidirectional handling or anything like that. > > The only slightly unusual thing is that a CAW command with a NUMBER OF > > LOGICAL BLOCKS equal to N will actually transfer 2*N worth of data -- > > one set of data for the compare operation and a second set to write if > > the compare succeeds. But just to be clear, the transfer of those 2*N > > blocks happens as a single transfer during the Data-Out phase. > > I think the confusion is that the implementation of COMPARE AND WRITE > obviously requires a read and a write phase, and the implementation > tries to mix this up with an actual bidirectional scsi command. > > If the core stopped keying off t_bidi_data_sg and used better flag > this could be easily solved. Good point here as well.. Changing these cases to check for SCF_BIDI instead, and adding a extra SCF_COMPARE_AND_WRITE check for the case in transport_generic_new_cmd() to call transport_generic_get_mem_bidi(). --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
