On Monday August 6, [EMAIL PROTECTED] wrote: > On Tue, 2007-08-07 at 16:07 +1000, Neil Brown wrote: > > Suppose that in a program I have an open file descriptor for a device, > > and I want to find the /sys/block information for this device. > > There is currently no direct way to do this. I need to read > > /sys/block/*/dev, /sys/block/*/*/dev > > and match major/minor numbers with the result from fstat. > > > > I would like a more direct mechanism. > > > > The following patch is a proposal for such a mechanism. > > > > It provides an 'ioctl' which returns then 'name' of the device, as > > generated by bdevname. This is the same name that is used to create > > entries in sysfs. > > For a partition of a device, it returns 'device/partition'. > > > how about returning the entire path relative to the start of sysfs? That > way, if things move or something you're tolerant against that....
That makes a lot of sense. So it would return "block/sda/sda1" now, but one day that might change to "class/block/sda/sda1" or some-such. > > (I'd not be against making this a generic IOCTL for every device, a > SYSFSLOCATION kind of ioctl... it's by no means block specific...) > That too seems very sensible. Only it's harder to choose a 'generic' ioctl request number than to choose a block-specific one :-) We would also need a somewhat longer buffer. The longest /sys/**/dev path on my test machine is /sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1:1.1/usb_endpoint/usbdev2.2_ep82/dev So at least 80 chars. Probably 256 would do.... #define SYSFSLOCATION _IOR(0, 0xff, char[256]) ?? Thanks, NeilBrown - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
