scsi-generic: Merge block max xfer len in INQUIRY response

The rationale is similar to the above mode sense response interception:
this is practically the only channel to communicate restraints from
elsewhere such as host and block driver.

The scsi bus we attach onto can have a larger max xfer len than what is
accepted by the host file system (guarding between the host scsi LUN and
QEMU), in which case the SG_IO we generate would get -EINVAL.
Signed-off-by: NFam Zheng <famz@redhat.com>
Message-Id: <1464243305-10661-3-git-send-email-famz@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/scsi/scsi-generic.c

@@ -222,6 +222,18 @@ static void scsi_read_complete(void * opaque, int ret)
             r->buf[3] |= 0x80;
         }
     }
+    if (s->type == TYPE_DISK &&
+        r->req.cmd.buf[0] == INQUIRY &&
+        r->req.cmd.buf[2] == 0xb0) {
+        uint32_t max_xfer_len = blk_get_max_transfer_length(s->conf.blk);
+        if (max_xfer_len) {
+            stl_be_p(&r->buf[8], max_xfer_len);
+            /* Also take care of the opt xfer len. */
+            if (ldl_be_p(&r->buf[12]) > max_xfer_len) {
+                stl_be_p(&r->buf[12], max_xfer_len);
+            }
+        }
+    }
     scsi_req_data(&r->req, len);
     scsi_req_unref(&r->req);
 }