[PATCH] vhost/scsi: truncate T10 PI iov_iter to prot_bytes

[Greg Edwards <gedwards@ddn.com>]

Commands with protection information included were not truncating the
protection iov_iter to the number of protection bytes in the command.
This resulted in vhost_scsi mis-calculating the size of the protection
SGL in vhost_scsi_calc_sgls(), and including both the protection and
data SG entries in the protection SGL.

Fixes: 09b13fa8c1a1 ("vhost/scsi: Add ANY_LAYOUT support in vhost_scsi_handle_vq")
Signed-off-by: Greg Edwards <gedwards@ddn.com>
---
 drivers/vhost/scsi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 76f8d649147b..cbe0ea26c1ff 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -964,7 +964,8 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
 				prot_bytes = vhost32_to_cpu(vq, v_req_pi.pi_bytesin);
 			}
 			/*
-			 * Set prot_iter to data_iter, and advance past any
+			 * Set prot_iter to data_iter and truncate it to
+			 * prot_bytes, and advance data_iter past any
 			 * preceeding prot_bytes that may be present.
 			 *
 			 * Also fix up the exp_data_len to reflect only the
@@ -973,6 +974,7 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
 			if (prot_bytes) {
 				exp_data_len -= prot_bytes;
 				prot_iter = data_iter;
+				iov_iter_truncate(&prot_iter, prot_bytes);
 				iov_iter_advance(&data_iter, prot_bytes);
 			}
 			tag = vhost64_to_cpu(vq, v_req_pi.tag);
-- 
2.17.1