Pull ITER_UBUF updates from Jens Axboe:
 "This turns singe vector imports into ITER_UBUF, rather than
  ITER_IOVEC.

  The former is more trivial to iterate and advance, and hence a bit
  more efficient. From some very unscientific testing, ~60% of all iovec
  imports are single vector"

* tag 'iter-ubuf.2-2023-04-21' of git://git.kernel.dk/linux:
  iov_iter: Mark copy_compat_iovec_from_user() noinline
  iov_iter: import single vector iovecs as ITER_UBUF
  iov_iter: convert import_single_range() to ITER_UBUF
  iov_iter: overlay struct iovec and ubuf/len
  iov_iter: set nr_segs = 1 for ITER_UBUF
  iov_iter: remove iov_iter_iovec()
  iov_iter: add iter_iov_addr() and iter_iov_len() helpers
  ALSA: pcm: check for user backed iterator, not specific iterator type
  IB/qib: check for user backed iterator, not specific iterator type
  IB/hfi1: check for user backed iterator, not specific iterator type
  iov_iter: add iter_iovec() helper
  block: ensure bio_alloc_map_data() deals with ITER_UBUF correctly