On Tue, 2013-08-20 at 23:35 -0700, Christoph Hellwig wrote: > On Tue, Aug 20, 2013 at 08:07:57PM +0000, Nicholas A. Bellinger wrote: > > From: Nicholas Bellinger <nab@xxxxxxxxxxxxx> > > > > COMPARE_AND_WRITE expects to be able to send down a DMA_FROM_DEVICE > > to obtain the necessary READ payload for comparision against the > > first half of the WRITE payload containing the verify user data. > > > > Currently virtual backends expect to internally reference SGLs, > > SGL nents, and data_direction, so change IBLOCK, FILEIO and RD > > sbc_ops->execute_rw() to accept this values as function parameters. > > > > Also add the sbc_execute_rw() wrapper to handle the special case > > for the initial COMPARE_AND_WRITE DMA_FROM_DEVICE -> READ I/O > > submission. > > I don't like the way this is structured with the new method. It seems > like we should just pass the sgl and associated data to execute_cmd > and have the read vs write logic driven by command code, using generic > flags instead of specificly checking for compare and write. I considered that approach as well, but in the end all of the non sbc_ops->execute_rw() users of se_cmd->execute_cmd() will never make use of a passed *sgl, sgl_nents, or data_direction that is different than se_cmd assignments. So in the end, the approach of changing all se_cmd->execute_cmd() users to accommodate COMPARE_AND_WRITE did not end up making sense outside of this particular special case.. --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
