target: Fail WRITE_SAME w/ UNMAP=1 when emulate_tpws=0

This patch adds a check within sbc_setup_write_same() to fail a
WRITE_SAME w/ UNMAP=1 op, if the backend device has emulate_tpws
disabled.

Cc: Martin Petersen <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c
index 856e800926b8..0d307c34f08e 100644
--- a/drivers/target/target_core_sbc.c
+++ b/drivers/target/target_core_sbc.c
@@ -293,6 +293,11 @@ sbc_setup_write_same(struct se_cmd *cmd, unsigned char *flags, struct sbc_ops *o
                 if (!ops->execute_write_same_unmap)
                         return TCM_UNSUPPORTED_SCSI_OPCODE;
 
+                if (!dev->dev_attrib.emulate_tpws) {
+                        pr_err("Got WRITE_SAME w/ UNMAP=1, but backend device"
+                               " has emulate_tpws disabled\n");
+                        return TCM_UNSUPPORTED_SCSI_OPCODE;
+                }
                 cmd->execute_cmd = ops->execute_write_same_unmap;
                 return 0;
         }