Commit 45097dae authored Apr 08, 2020 by Xiaoguang Wang Committed by Jens Axboe Apr 08, 2020

io_uring: do not always copy iovec in io_req_map_rw()



In io_read_prep() or io_write_prep(), io_req_map_rw() takes
struct io_async_rw's fast_iov as argument to call io_import_iovec(),
and if io_import_iovec() uses struct io_async_rw's fast_iov as
valid iovec array, later indeed io_req_map_rw() does not need
to do the memcpy operation, because they are same pointers.

Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent 08a1d26e

fs/io_uring.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -2493,6 +2493,7 @@ static void io_req_map_rw(struct io_kiocb *req, ssize_t io_size,
		req->io->rw.iov = iovec;
		if (!req->io->rw.iov) {
		req->io->rw.iov = req->io->rw.fast_iov;
		if (req->io->rw.iov != fast_iov)
		memcpy(req->io->rw.iov, fast_iov,
		sizeof(struct iovec) * iter->nr_segs);
		} else {

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