[patch] extending alloc_unr(9) to allocate specific unit numbers

[Jaakko Heinonen]

Hi,

I wrote a patch to extend the kernel unit number allocator for
allocating specific unit numbers. The patch adds a new function
alloc_unr_specific() which returns the requested unit number if it is
free and -1 if the number is already allocated or out of the range.
Unlike alloc_unr(), alloc_unr_specific() may allocate memory and thus
sleep.

The patch is here:

	http://people.freebsd.org/~jh/patches/alloc_unr_specific.diff

I think that this functionality has been requested by some people.
Reviews/comments?

As an example here is md(4) converted to use
alloc_unr() / alloc_unr_specific():

	http://people.freebsd.org/~jh/patches/md-alloc_unr.diff

-- 
Jaakko