Commit 9221d2e3 authored by Al Viro's avatar Al Viro
Browse files

iov_iter_alignment(): don't bother with iterate_all_kinds() 



It's easier to go over the array manually.  We need to watch out
for truncated iov_iter, though - iovec array might cover more
than i->count.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 8409a0d2

lib/iov_iter.c

+53 −10
Original line number Diff line number Diff line
@@ -1328,27 +1328,70 @@ void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count) 
}

EXPORT_SYMBOL(iov_iter_discard);



unsigned long iov_iter_alignment(const struct iov_iter *i)

static unsigned long iov_iter_alignment_iovec(const struct iov_iter *i)

{

	unsigned long res = 0;

	size_t size = i->count;

	size_t skip = i->iov_offset;

	unsigned k;



	for (k = 0; k < i->nr_segs; k++, skip = 0) {

		size_t len = i->iov[k].iov_len - skip;

		if (len) {

			res |= (unsigned long)i->iov[k].iov_base + skip;

			if (len > size)

				len = size;

			res |= len;

			size -= len;

			if (!size)

				break;

		}

	}

	return res;

}



	if (unlikely(iov_iter_is_pipe(i))) {

static unsigned long iov_iter_alignment_bvec(const struct iov_iter *i)

{

	unsigned res = 0;

	size_t size = i->count;

	unsigned skip = i->iov_offset;

	unsigned k;



	for (k = 0; k < i->nr_segs; k++, skip = 0) {

		size_t len = i->bvec[k].bv_len - skip;

		res |= (unsigned long)i->bvec[k].bv_offset + skip;

		if (len > size)

			len = size;

		res |= len;

		size -= len;

		if (!size)

			break;

	}

	return res;

}



unsigned long iov_iter_alignment(const struct iov_iter *i)

{

	/* iovec and kvec have identical layouts */

	if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))

		return iov_iter_alignment_iovec(i);



	if (iov_iter_is_bvec(i))

		return iov_iter_alignment_bvec(i);



	if (iov_iter_is_pipe(i)) {

		unsigned int p_mask = i->pipe->ring_size - 1;

		size_t size = i->count;



		if (size && i->iov_offset && allocated(&i->pipe->bufs[i->head & p_mask]))

			return size | i->iov_offset;

		return size;

	}

	if (unlikely(iov_iter_is_xarray(i)))



	if (iov_iter_is_xarray(i))

		return (i->xarray_start + i->iov_offset) | i->count;

	iterate_all_kinds(i, size, v,

		(res |= (unsigned long)v.iov_base | v.iov_len, 0),

		res |= v.bv_offset | v.bv_len,

		res |= (unsigned long)v.iov_base | v.iov_len,

		res |= v.bv_offset | v.bv_len

	)

	return res;



	return 0;

}

EXPORT_SYMBOL(iov_iter_alignment);