On Mon, May 28, 2007 at 11:30:32AM +1000, Neil Brown wrote: > 1/ A BIO_RW_BARRIER request should never fail with -EOPNOTSUP. The device-mapper position has always been that we require > a zero-length BIO_RW_BARRIER (i.e. containing no data to read or write - or emulated, possibly device-specific) before we can provide full barrier support. (Consider multiple active paths - each must see barrier.) Until every device supports barriers -EOPNOTSUP support is required. (Consider reconfiguration of stacks of devices - barrier support is a dynamic block device property that can switch between available and unavailable at any time.) Alasdair -- agk@xxxxxxxxxx - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
