Messages in this thread | | | From | Neil Brown <> | Date | Fri, 16 Dec 2005 14:36:19 +1100 | Subject | Re: sysfs question: how to map major:minor to name under /sys |
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On Thursday December 15, greg@kroah.com wrote: > On Thu, Dec 15, 2005 at 02:14:06PM +1100, Neil Brown wrote: > > > > Hi, > > I have a question about sysfs related usage. > > > > Suppose I have a major:minor number for a block device - maybe from > > fstat of a filedescriptor I was given, or stat of a name in /dev. > > How do I find the directory in /sys/block that contains relevant > > information? > > > > It seems to me that there is no direct way, and maybe there should > > be. (I can do a find of 'dev' file and compare, which is fine in a > > one-off shell script, but sub-optimal in general). > > So you want this info from userspace, not from within the kernel, > right?
Right.
> > > The most obvious solution would be to have a directory somewhere full > > of symlinks: > > /sys/block_dev/8:0 -> ../block/sda > > or whatever. > > Is this reasonable? Should I try it? > > It seems a bit md specific to add a lot of kernel code for something > that can be solved with a userspace shell script :)
I don't see it as md specific. Suppose I want to change the IO scheduler under the filesystem /foo. I look that up in mtab and find it is mounted on /dev/blah. To find the corresponding /sys/block entry I have to search. That's fine if I only have a few block devices. But I keep hearing storing of people with thousands. Having to search just feels clumsy.
> > But if you want to try it, use a class, and a class_device for this, not > raw kobjects. It should be a bit easier that way.
Well, maybe it'll be a good excuse to learn more about 'class' and 'class_device' anyway. Thanks, NeilBrown - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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