We can do better than generic iterate_and_advance() for this one;
inspired by bvec_iter_advance() (and massaged into that form by
equivalent transformations).
[fixed a braino caught by kernel test robot <oliver.sang@xxxxxxxxx>]
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
lib/iov_iter.c | 42 ++++++++++++++++++++++++++++--------------
1 file changed, 28 insertions(+), 14 deletions(-)
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 5a02c94a51ab..5621a3457118 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1107,28 +1107,42 @@ static void iov_iter_bvec_advance(struct iov_iter *i, size_t size)
i->iov_offset = bi.bi_bvec_done;
}
+static void iov_iter_iovec_advance(struct iov_iter *i, size_t size)
+{
+ const struct iovec *iov, *end;
+
+ if (!i->count)
+ return;
+ i->count -= size;
+
+ size += i->iov_offset; // from beginning of current segment
+ for (iov = i->iov, end = iov + i->nr_segs; iov < end; iov++) {
+ if (likely(size < iov->iov_len))
+ break;
+ size -= iov->iov_len;
+ }
+ i->iov_offset = size;
+ i->nr_segs -= iov - i->iov;
+ i->iov = iov;
+}
+
void iov_iter_advance(struct iov_iter *i, size_t size)
{
if (unlikely(i->count < size))
size = i->count;
- if (unlikely(iov_iter_is_pipe(i))) {
+ if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) {
+ /* iovec and kvec have identical layouts */
+ iov_iter_iovec_advance(i, size);
+ } else if (iov_iter_is_bvec(i)) {
+ iov_iter_bvec_advance(i, size);
+ } else if (iov_iter_is_pipe(i)) {
pipe_advance(i, size);
- return;
- }
- if (unlikely(iov_iter_is_discard(i))) {
- i->count -= size;
- return;
- }
- if (unlikely(iov_iter_is_xarray(i))) {
+ } else if (unlikely(iov_iter_is_xarray(i))) {
i->iov_offset += size;
i->count -= size;
- return;
- }
- if (iov_iter_is_bvec(i)) {
- iov_iter_bvec_advance(i, size);
- return;
+ } else if (iov_iter_is_discard(i)) {
+ i->count -= size;
}
- iterate_and_advance(i, size, v, 0, 0, 0, 0)
}
EXPORT_SYMBOL(iov_iter_advance);
--
2.11.0
