3.3-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Roland Dreier <redacted>

commit 6cf3fa6918baab0c447f1206f1cef9166ad04864 upstream.

If the target core signals an over- or under-run, tcm_loop should call
scsi_set_resid() to tell the SCSI midlayer about the residual data length.

The difference can be seen by doing something like

    strace -eioctl sg_raw -r 1024 /dev/sda 8 0 0 0 1 0 > /dev/null

and looking at the "resid=" part of the SG_IO ioctl -- after this patch,
the field is correctly reported as 512.

Signed-off-by: Roland Dreier <redacted>
Signed-off-by: Nicholas Bellinger <redacted>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/target/loopback/tcm_loop.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/target/loopback/tcm_loop.c
+++ b/drivers/target/loopback/tcm_loop.c

@@ -855,6 +855,9 @@ static int tcm_loop_queue_data_in(struct
 
 	sc->result = SAM_STAT_GOOD;
 	set_host_byte(sc, DID_OK);
+	if ((se_cmd->se_cmd_flags & SCF_OVERFLOW_BIT) ||
+	    (se_cmd->se_cmd_flags & SCF_UNDERFLOW_BIT))
+		scsi_set_resid(sc, se_cmd->residual_count);
 	sc->scsi_done(sc);
 	return 0;
 }

@@ -880,6 +883,9 @@ static int tcm_loop_queue_status(struct
 		sc->result = se_cmd->scsi_status;
 
 	set_host_byte(sc, DID_OK);
+	if ((se_cmd->se_cmd_flags & SCF_OVERFLOW_BIT) ||
+	    (se_cmd->se_cmd_flags & SCF_UNDERFLOW_BIT))
+		scsi_set_resid(sc, se_cmd->residual_count);
 	sc->scsi_done(sc);
 	return 0;
 }