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: NEric Sandeen <sandeen@redhat.com>
Reviewed-by: NAndreas Dilger <adilger@whamcloud.com>
Signed-off-by: NJan Kara <jack@suse.cz>

fs/ext3/super.c

@@ -2058,7 +2058,8 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
 		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);