vt/fbcon: fix background color on line feed

Another addendum to commit c9e587ab
("vt: fix background color on line feed").

fbcon still was not doing the right thing (read: continued to do old
behavior).  fbcon_clear() seems to clear the new line (e.g.  where your new
prompt appears after doing echo -en "\e[42mfoo\n"), while scr_memsetw clears
the previous one only (where "foo" appears).  So just temporarily set the
video_erase_char to the scrl_erase_char so that fbcon_clear does the right
thing.
Signed-off-by: NJan Engelhardt <jengelh@medozas.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/video/console/fbcon.c

@@ -1853,6 +1853,8 @@ static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
 	struct fb_info *info = registered_fb[con2fb_map[vc->vc_num]];
 	struct display *p = &fb_display[vc->vc_num];
 	int scroll_partial = info->flags & FBINFO_PARTIAL_PAN_OK;
+	unsigned short saved_ec;
+	int ret;
 
 	if (fbcon_is_inactive(vc, info))
 		return -EINVAL;
@@ -1865,6 +1867,11 @@ static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
 	 *           whole screen (prevents flicker).
 	 */
 
+	saved_ec = vc->vc_video_erase_char;
+	vc->vc_video_erase_char = vc->vc_scrl_erase_char;
+
+	ret = 0;
+
 	switch (dir) {
 	case SM_UP:
 		if (count > vc->vc_rows)	/* Maximum realistic size */
@@ -1883,7 +1890,7 @@ static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
 							(b - count)),
 				    vc->vc_scrl_erase_char,
 				    vc->vc_size_row * count);
-			return 1;
+			ret = 1;
 			break;
 
 		case SCROLL_WRAP_MOVE:
@@ -1955,7 +1962,8 @@ static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
 							(b - count)),
 				    vc->vc_scrl_erase_char,
 				    vc->vc_size_row * count);
-			return 1;
+			ret = 1;
+			break;
 		}
 		break;
 
@@ -1974,7 +1982,7 @@ static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
 							t),
 				    vc->vc_scrl_erase_char,
 				    vc->vc_size_row * count);
-			return 1;
+			ret = 1;
 			break;
 
 		case SCROLL_WRAP_MOVE:
@@ -2044,10 +2052,13 @@ static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
 							t),
 				    vc->vc_scrl_erase_char,
 				    vc->vc_size_row * count);
-			return 1;
+			ret = 1;
+			break;
 		}
+		break;
 	}
-	return 0;
+	vc->vc_video_erase_char = saved_ec;
+	return ret;
 }