Btrfs: prohibit a operation of changing acl's mask when noacl mount option used

when used Posix File System Test Suite(pjd-fstest) to test btrfs,
some cases about setfacl failed when noacl mount option used.
I simplified used commands in pjd-fstest, and the following steps
can reproduce it.
------------------------
# cd btrfs-part/
# mkdir aaa
# setfacl -m m::rw aaa    <- successed, but not expected by pjd-fstest.
------------------------
I checked ext3, a warning message occured, like as:
  setfacl: aaa/: Operation not supported
Certainly, it's expected by pjd-fstest.

So, i compared acl.c of btrfs and ext3. Based on that, a patch created.
Fortunately, it works.

Signed-off-by: Shi Weihua <shiwh@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/acl.c

@@ -163,6 +163,9 @@ static int btrfs_xattr_acl_set(struct dentry *dentry, const char *name,
 	if (!is_owner_or_cap(dentry->d_inode))
 		return -EPERM;
 
+	if (!IS_POSIXACL(dentry->d_inode))
+		return -EOPNOTSUPP;
+
 	if (value) {
 		acl = posix_acl_from_xattr(value, size);
 		if (acl == NULL) {