ext3: force ro mount if ext3_setup_super() fails

If ext3_setup_super() fails i.e. due to a too-high revision,
the error is logged in dmesg but the fs is not mounted RO as
indicated.

Tested by:

[164152.114551] EXT3-fs (sdb6): error: revision level too high, forcing read-only mode
/dev/sdb6 /mnt/test2 ext3 rw,seclabel,relatime,errors=continue,user_xattr,acl,barrier=1,data=ordered 0 0
^^

Signed-off-by: Eric Sandeen <[e-mail]>
Reviewed-by: Andreas Dilger <[e-mail]>
Signed-off-by: Jan Kara <[e-mail]>

fs/ext3/super.c

···
 		goto failed_mount3;
 	}
 
-	ext3_setup_super (sb, es, sb->s_flags & MS_RDONLY);
+	if (ext3_setup_super(sb, es, sb->s_flags & MS_RDONLY))
+		sb->s_flags |= MS_RDONLY;
 
 	EXT3_SB(sb)->s_mount_state |= EXT3_ORPHAN_FS;
 	ext3_orphan_cleanup(sb, es);