libata: Fixup n_elem initialization
Fixup the inialization of qc->n_elem. It currently gets
initialized to 1 for commands that do not transfer any data.
Fix this by initializing n_elem to 0 and only setting to 1
in ata_scsi_qc_new when there is data to transfer. This fixes
some problems seen with SATA devices attached to ipr adapters.
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 836947d..7cc5a4a 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -372,7 +372,7 @@
if (cmd->use_sg) {
qc->__sg = (struct scatterlist *) cmd->request_buffer;
qc->n_elem = cmd->use_sg;
- } else {
+ } else if (cmd->request_bufflen) {
qc->__sg = &qc->sgent;
qc->n_elem = 1;
}
diff --git a/include/linux/libata.h b/include/linux/libata.h
index e53a13b..65d3187 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -1149,6 +1149,7 @@
qc->cursect = qc->cursg = qc->cursg_ofs = 0;
qc->nsect = 0;
qc->nbytes = qc->curbytes = 0;
+ qc->n_elem = 0;
qc->err_mask = 0;
ata_tf_init(qc->dev, &qc->tf);