>>>>> "Andreas" == Andreas Dilger <adilger@xxxxxxx> writes: Andreas> Having an ioctl() that can be called on the block device Andreas> (getting the right device regardless of its name) seems a lot Andreas> more useful to applications in my experience, unless you are Andreas> using a script. The reason I didn't do it that way is that I only exported the bare bones required for userland to deal with the layout intelligently. The problem of the ioctl is that you lose information about the subdevices and in particular about their physical alignment. The phys_off value I export for the MD device is the offset for the first device. But that does not imply that the other devices in the stripe have the same alignment. I considered taking an approach similar to blk_queue_stack_limits() where you clamp using the existing values as you add more devices. The downside to that is that you really want to let the user know that there's a potential problem. And requiring the user to scrounge through syslog to look for complaints isn't so happening. I'd much rather do that in libdisk where it's easy to print a message about "Suboptimal layout, proceed with caution". IOW, the idea is (for better and for worse) to let libdisk traverse sysfs to ensure that all things line up nicely before mkfs actually starts writing. -- Martin K. Petersen Oracle Linux Engineering -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
