On Thu, 2008-10-02 at 07:45 -0600, Chris Worley wrote: > In perusing the "discard-2.6" kernel at infradead.org (great job... I > have a device I'm testing it on, and it's working), I'm unclear on > what I'm supposed to do in the prepare_discard_fn function. > > It looks like, if it exists, the the discard bio gets passed to the > normal handler. Otherwise, it seems to have no duties. I'm guessing > it's for whatever initialization is needed for the device... but > checking to be sure. It's intended to prepare the command which will be sent to the device, much like the prepare_flush_fn does. See sd_prepare_flush() in drivers/scsi/sd.c for an example (all the devices we've hooked up for discard in Linux so far are virtual ones, so they don't make good examples). I do have a real ATA drive with TRIM protocol support on its way to me though, so I'll be looking at that some time soon. -- David Woodhouse Open Source Technology Centre David.Woodhouse@xxxxxxxxx Intel Corporation -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
