MFC r322459,322897
The *_meta_* functions include a radix parameter, a blk parameter, and another parameter that identifies a starting point in the memory address block. Radix is a power of two, blk is a multiple of radix, and the starting point is in the range [blk, blk+radix), so that blk can always be computed from the other two. This change drops the blk parameter from the meta functions and computes it instead. (On amd64, for example, this change reduces subr_blist.o's text size by 7%.) It also makes the radix parameters unsigned to address concerns that the calculation of '-radix' might overflow without the -fwrapv option. (See https://reviews.freebsd.org/D11819.) Correct a regression in the previous change, r322459. Specifically, the removal of the "blk" parameter from blst_meta_alloc() had the unintended effect of generating an out-of-range allocation when the cursor reaches the end of the tree if the number of managed blocks in the tree equals the so-called "radix" (which in the blist code is not the standard notion of what a radix is but rather the maximum number of leaves in a tree of the current height.) In other words, only certain swap configurations were affected, which is why earlier testing did not reveal the problem.