1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index 76555b1ddfd5..8aeaad95242c 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -109,6 +109,16 @@ static int smp_execute_task(struct domain_device *dev, void *req, int req_size,
                     task->task_status.stat == SAM_GOOD) {
                         res = 0;
                         break;
+                } if (task->task_status.resp == SAS_TASK_COMPLETE &&
+                      task->task_status.stat == SAS_DATA_UNDERRUN) {
+                        /* no error, but return the number of bytes of
+                         * underrun */
+                        res = task->task_status.residual;
+                        break;
+                } if (task->task_status.resp == SAS_TASK_COMPLETE &&
+                      task->task_status.stat == SAS_DATA_OVERRUN) {
+                        res = -EMSGSIZE;
+                        break;
                 } else {
                         SAS_DPRINTK("%s: task to dev %016llx response: 0x%x "
                                     "status 0x%x\n", __FUNCTION__,
@@ -1924,6 +1934,15 @@ int sas_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy,
 
         ret = smp_execute_task(dev, bio_data(req->bio), req->data_len,
                                bio_data(rsp->bio), rsp->data_len);
+        if (ret > 0) {
+                /* positive number is the untransferred residual */
+                rsp->data_len = ret;
+                req->data_len = 0;
+                ret = 0;
+        } else if (ret == 0) {
+                rsp->data_len = 0;
+                req->data_len = 0;
+        }
 
         return ret;
 }