Re: [PATCH 1/4] util/iov: Make qiov_slice() public

[Eric Blake]

On Fri, Mar 17, 2023 at 06:50:16PM +0100, Hanna Czenczek wrote:
> We want to inline qemu_iovec_init_extended() in block/io.c for padding
> requests, and having access to qiov_slice() is useful for this.
> 
> (We will need to count the number of I/O vector elements of a slice
> there, and then later process this slice.  Without qiov_slice(), we
> would need to call qemu_iovec_subvec_niov(), and all further
> IOV-processing functions may need to skip prefixing elements to
> accomodate for a qiov_offset.  Because qemu_iovec_subvec_niov()
> internally calls qiov_slice(), we can just have the block/io.c code call
> qiov_slice() itself, thus get the number of elements, and also create an
> iovec array with the superfluous prefixing elements stripped, so the
> following processing functions no longer need to skip them.)

Might be worth mentioning in the commit message that you also renamed
it to qemu_iovec_slice() as part of exporting.

> 
> Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
> ---
>  include/qemu/iov.h |  3 +++
>  util/iov.c         | 14 +++++++-------
>  2 files changed, 10 insertions(+), 7 deletions(-)

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org