Commit 59852eba authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring/rsrc: refactor io_import_fixed 



io_import_fixed is a mess. Even though we know the final len of the
iterator, we still assign offset + len and do some magic after to
correct for that.

Do offset calculation first and finalise it with iov_iter_bvec at the
end.

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/2d5107fed24f8b23245ef2ede9a5a7f7c426df61.1744882081.git.asml.silence@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 50169d07

io_uring/rsrc.c

+7 −17
Original line number Diff line number Diff line
@@ -1037,6 +1037,7 @@ static int io_import_fixed(int ddir, struct iov_iter *iter, 
			   u64 buf_addr, size_t len)

{

	const struct bio_vec *bvec;

	unsigned nr_segs;

	size_t offset;

	int ret;
@@ -1056,8 +1057,6 @@ static int io_import_fixed(int ddir, struct iov_iter *iter, 
		return 0;

	}



	iov_iter_bvec(iter, ddir, imu->bvec, imu->nr_bvecs, offset + len);



	/*

	 * Don't use iov_iter_advance() here, as it's really slow for

	 * using the latter parts of a big fixed buffer - it iterates
@@ -1067,30 +1066,21 @@ static int io_import_fixed(int ddir, struct iov_iter *iter, 
	 * 1) it's a BVEC iter, we set it up

	 * 2) all bvecs are the same in size, except potentially the

	 *    first and last bvec

	 *

	 * So just find our index, and adjust the iterator afterwards.

	 * If the offset is within the first bvec (or the whole first

	 * bvec, just use iov_iter_advance(). This makes it easier

	 * since we can just skip the first segment, which may not

	 * be folio_size aligned.

	 */

	bvec = imu->bvec;

	if (offset < bvec->bv_len) {

		iter->count -= offset;

		iter->iov_offset = offset;

	} else {

	if (offset >= bvec->bv_len) {

		unsigned long seg_skip;



		/* skip first vec */

		offset -= bvec->bv_len;

		seg_skip = 1 + (offset >> imu->folio_shift);



		iter->bvec += seg_skip;

		iter->nr_segs -= seg_skip;

		iter->count -= bvec->bv_len + offset;

		iter->iov_offset = offset & ((1UL << imu->folio_shift) - 1);

		bvec += seg_skip;

		offset &= (1UL << imu->folio_shift) - 1;

	}



	nr_segs = imu->nr_bvecs - (bvec - imu->bvec);

	iov_iter_bvec(iter, ddir, bvec, nr_segs, len);

	iter->iov_offset = offset;

	return 0;

}