Kay Sievers wrote: > On Mon, 2007-12-17 at 09:43 +1100, Neil Brown wrote: >> On Saturday December 15, [EMAIL PROTECTED] wrote: >>> On Dec 14, 2007 7:26 AM, NeilBrown <[EMAIL PROTECTED]> wrote: >>>> Given an fd on a block device, returns a string like >>>> >>>> /block/sda/sda1 >>>> >>>> which can be used to find related information in /sys. >> .... >>> As pointed out to when you came up with the idea, we can't do this. A >>> devpath >>> is a path to the device and will not necessarily start with "/block" for >>> block >>> devices. It may start with "/devices" and can be much longer than >>> BDEVNAME_SIZE*2 + 10. >> When you say "will not necessarily" can I take that to mean that it >> currently does, but it might (will) change?? > > It's in -mm. The devpath for all block devices, like for all other > devices, will start with /devices/* if !SYSFS_DEPRECATED.
This is the second time I come across this (planned?) change, and for the second time I can't understand it. How to distinguish char devices from block devices in sysfs? Is the only way to read a symlink `subsystem' in the device directory? For now, I've a shell code (used heavily in numerous places), which looks like this: function makedev() { ... case $DEVPATH in /block/*) TYPE=b ;; *) TYPE=c ;; esac ... mknod /dev/$DEV $TYPE $MAJOR $MINOR } The only external process invocation in there is mknod, all the rest is done using pure shell constructs. Is it really necessary to spawn another process just to read a symlink now? It will be almost 2 times slower.... (Sure thing this may be rewritten in C, but using shell it's MUCH easier to customize if necessary.) Also, /sys/block/ directory is very easy to use currently, -- unlike other /sys/ stuff which is way too deep and often placed in unknown/unexpected places (and /sys/class/ and /sys/bus/ directories are changing all the time). What's the benefit of moving things from /sys/block/ to /sys/devices/ ? Thanks. /mjt -- 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/