| Message ID | 20220622041552.737754-11-viro@zeniv.linux.org.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [01/44] 9p: handling Rerror without copy_from_iter_full() | expand |
On Wed, 2022-06-22 at 05:15 +0100, Al Viro wrote: > do what we do for iovec/kvec; that ends up generating better code, > AFAICS. > > Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> > --- > lib/iov_iter.c | 23 ++++++++++++++--------- > 1 file changed, 14 insertions(+), 9 deletions(-) > > diff --git a/lib/iov_iter.c b/lib/iov_iter.c > index 8275b28e886b..93ceb13ec7b5 100644 > --- a/lib/iov_iter.c > +++ b/lib/iov_iter.c > @@ -870,17 +870,22 @@ static void pipe_advance(struct iov_iter *i, size_t size) > > static void iov_iter_bvec_advance(struct iov_iter *i, size_t size) > { > - struct bvec_iter bi; > + const struct bio_vec *bvec, *end; > > - bi.bi_size = i->count; > - bi.bi_bvec_done = i->iov_offset; > - bi.bi_idx = 0; > - bvec_iter_advance(i->bvec, &bi, size); > + if (!i->count) > + return; > + i->count -= size; > + > + size += i->iov_offset; > > - i->bvec += bi.bi_idx; > - i->nr_segs -= bi.bi_idx; > - i->count = bi.bi_size; > - i->iov_offset = bi.bi_bvec_done; > + for (bvec = i->bvec, end = bvec + i->nr_segs; bvec < end; bvec++) { > + if (likely(size < bvec->bv_len)) > + break; > + size -= bvec->bv_len; > + } > + i->iov_offset = size; > + i->nr_segs -= bvec - i->bvec; > + i->bvec = bvec; > } > > static void iov_iter_iovec_advance(struct iov_iter *i, size_t size) Much simpler to follow, IMO... Reviewed-by: Jeff Layton <jlayton@kernel.org>
On Wed, Jun 22, 2022 at 05:15:19AM +0100, Al Viro wrote: > do what we do for iovec/kvec; that ends up generating better code, > AFAICS. > > Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> > --- Looks good to me, Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 8275b28e886b..93ceb13ec7b5 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -870,17 +870,22 @@ static void pipe_advance(struct iov_iter *i, size_t size) static void iov_iter_bvec_advance(struct iov_iter *i, size_t size) { - struct bvec_iter bi; + const struct bio_vec *bvec, *end; - bi.bi_size = i->count; - bi.bi_bvec_done = i->iov_offset; - bi.bi_idx = 0; - bvec_iter_advance(i->bvec, &bi, size); + if (!i->count) + return; + i->count -= size; + + size += i->iov_offset; - i->bvec += bi.bi_idx; - i->nr_segs -= bi.bi_idx; - i->count = bi.bi_size; - i->iov_offset = bi.bi_bvec_done; + for (bvec = i->bvec, end = bvec + i->nr_segs; bvec < end; bvec++) { + if (likely(size < bvec->bv_len)) + break; + size -= bvec->bv_len; + } + i->iov_offset = size; + i->nr_segs -= bvec - i->bvec; + i->bvec = bvec; } static void iov_iter_iovec_advance(struct iov_iter *i, size_t size)
do what we do for iovec/kvec; that ends up generating better code, AFAICS. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> --- lib/iov_iter.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-)