xfs: invalidate cached acl if set via ioctl

Setting or removing the "SGI_ACL_[FILE|DEFAULT]" attributes via the
XFS_IOC_ATTRMULTI_BY_HANDLE ioctl completely bypasses the POSIX ACL
infrastructure, like setting the "trusted.SGI_ACL_[FILE|DEFAULT]" xattrs
did until commit 6caa1056.  Similar to that commit, invalidate cached
acls when setting/removing them via the ioctl as well.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/xfs_acl.h b/fs/xfs/xfs_acl.h
index 3841b07..75af0a4 100644
--- a/fs/xfs/xfs_acl.h
+++ b/fs/xfs/xfs_acl.h
@@ -36,4 +36,7 @@
 # define posix_acl_access_exists(inode)			0
 # define posix_acl_default_exists(inode)		0
 #endif /* CONFIG_XFS_POSIX_ACL */
+
+extern void xfs_forget_acl(struct inode *inode, const char *name, int xflags);
+
 #endif	/* __XFS_ACL_H__ */