[PATCH v2 5/7] iov_iter: optimise bvec iov_iter_advance()
From: Pavel Begunkov <asml.silence@gmail.com>
Date: 2021-01-02 15:23:42
Also in:
linux-block, linux-doc, linux-fsdevel, linux-scsi, linux-xfs, lkml, target-devel
Subsystem:
library code, the rest, userspace copyin/copyout (uiovec) · Maintainers:
Andrew Morton, Linus Torvalds, Alexander Viro
iov_iter_advance() is heavily used, but implemented through generic means. For bvecs there is a specifically crafted function for that, so use bvec_iter_advance() instead, it's faster and slimmer. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> --- lib/iov_iter.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 7de304269641..9b1c109dc8a9 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c@@ -1065,6 +1065,21 @@ static void pipe_advance(struct iov_iter *i, size_t size) pipe_truncate(i); } +static void iov_iter_bvec_advance(struct iov_iter *i, size_t size) +{ + struct bvec_iter bi; + + bi.bi_size = i->count; + bi.bi_bvec_done = i->iov_offset; + bi.bi_idx = 0; + bvec_iter_advance(i->bvec, &bi, size); + + i->bvec += bi.bi_idx; + i->nr_segs -= bi.bi_idx; + i->count = bi.bi_size; + i->iov_offset = bi.bi_bvec_done; +} + void iov_iter_advance(struct iov_iter *i, size_t size) { if (unlikely(iov_iter_is_pipe(i))) {
@@ -1075,6 +1090,10 @@ void iov_iter_advance(struct iov_iter *i, size_t size) i->count -= size; return; } + if (iov_iter_is_bvec(i)) { + iov_iter_bvec_advance(i, size); + return; + } iterate_and_advance(i, size, v, 0, 0, 0) } EXPORT_SYMBOL(iov_iter_advance);
--
2.24.0