On Tuesday February 10, thomas@horsten.com wrote: > Hi, > > I'm writing a userspace utility to detect/configure Medley (and later > other) ataraid devices in 2.6. ... > > On top of this it would be useful to make the underlying devices > inaccessible after the mapped device is created (to prevent people from > doing things like fdisk /dev/hda, when what they really wanted was > something like fdisk /dev/ataraid/disc). The best way to avoid this sort of problem is to change "fdisk" (and mkfs and fsck and ...) to (optionally) open the device with O_EXCL. In 2.6, a device that is "claimed" by a kernel subsystem - ie is mounted, or is part of an MD or DM array, or has a partition which is claimed in one of these ways, cannot be opened O_EXCL. So these tools that operate on block devices and expect exclusive access should ask for it. They probably should have a way to not use O_EXCL if the admin promises they know what they are doing, as fsck does need to run on a mounted partition some times, and fdisk can reasonably be used on devices with mounted partitions. But the default should be O_EXCL. NeilBrown > > Detecting the partition table in userspace would fix this, but it's not > planned before 2.7 and I don't think it is safe to leave the false > partitions exposed. > > - Some RAID types will need (I think) to use the MD framework as well as > DM (e.g. RAID0+1), so the device the users would be the md device which > would be composed of two dm devices. Is there a way to hide the underlying > dm devices from the user so he they only see the ones they should use (or > prevent these from being used directly some other way)? > > // Thomas > > - > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
