Commit fa15bafb authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: flip if handling after io_setup_async_rw 



As recently done with with send/recv, flip the if after
rw_verify_aread() in io_{read,write}() and tabulise left bits left.
This removes mispredicted by a compiler jump on the success/fast path.

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 1752f0ad

fs/io_uring.c

+72 −74
Original line number Diff line number Diff line
@@ -3034,28 +3034,28 @@ static int io_read(struct io_kiocb *req, bool force_nonblock, 
	struct kiocb *kiocb = &req->rw.kiocb;

	struct iov_iter iter;

	size_t iov_count;

	ssize_t io_size, ret;

	ssize_t io_size, ret, ret2;

	unsigned long nr_segs;



	ret = io_import_iovec(READ, req, &iovec, &iter, !force_nonblock);

	if (ret < 0)

		return ret;

	io_size = ret;

	req->result = io_size;



	/* Ensure we clear previously set non-block flag */

	if (!force_nonblock)

		kiocb->ki_flags &= ~IOCB_NOWAIT;



	io_size = ret;

	req->result = io_size;



	/* If the file doesn't support async, just async punt */

	if (force_nonblock && !io_file_supports_async(req->file, READ))

		goto copy_iov;



	iov_count = iov_iter_count(&iter);

	nr_segs = iter.nr_segs;

	ret = rw_verify_area(READ, req->file, &kiocb->ki_pos, iov_count);

	if (!ret) {

		unsigned long nr_segs = iter.nr_segs;

		ssize_t ret2 = 0;

	if (unlikely(ret))

		goto out_free;



	ret2 = io_iter_do_read(req, &iter);
@@ -3066,8 +3066,8 @@ static int io_read(struct io_kiocb *req, bool force_nonblock, 
		iter.count = iov_count;

		iter.nr_segs = nr_segs;

copy_iov:

			ret = io_setup_async_rw(req, io_size, iovec,

						inline_vecs, &iter);

		ret = io_setup_async_rw(req, io_size, iovec, inline_vecs,

					&iter);

		if (ret)

			goto out_free;

		/* it's copied and will be cleaned with ->io */
@@ -3085,7 +3085,6 @@ copy_iov: 
		kiocb->ki_flags &= ~IOCB_WAITQ;

		return -EAGAIN;

	}

	}

out_free:

	if (iovec)

		kfree(iovec);
@@ -3117,19 +3116,19 @@ static int io_write(struct io_kiocb *req, bool force_nonblock, 
	struct kiocb *kiocb = &req->rw.kiocb;

	struct iov_iter iter;

	size_t iov_count;

	ssize_t ret, io_size;

	ssize_t ret, ret2, io_size;

	unsigned long nr_segs;



	ret = io_import_iovec(WRITE, req, &iovec, &iter, !force_nonblock);

	if (ret < 0)

		return ret;

	io_size = ret;

	req->result = io_size;



	/* Ensure we clear previously set non-block flag */

	if (!force_nonblock)

		req->rw.kiocb.ki_flags &= ~IOCB_NOWAIT;



	io_size = ret;

	req->result = io_size;



	/* If the file doesn't support async, just async punt */

	if (force_nonblock && !io_file_supports_async(req->file, WRITE))

		goto copy_iov;
@@ -3140,10 +3139,10 @@ static int io_write(struct io_kiocb *req, bool force_nonblock, 
		goto copy_iov;



	iov_count = iov_iter_count(&iter);

	nr_segs = iter.nr_segs;

	ret = rw_verify_area(WRITE, req->file, &kiocb->ki_pos, iov_count);

	if (!ret) {

		unsigned long nr_segs = iter.nr_segs;

		ssize_t ret2;

	if (unlikely(ret))

		goto out_free;



	/*

	 * Open-code file_start_write here to grab freeze protection,
@@ -3177,15 +3176,14 @@ static int io_write(struct io_kiocb *req, bool force_nonblock, 
		iter.count = iov_count;

		iter.nr_segs = nr_segs;

copy_iov:

			ret = io_setup_async_rw(req, io_size, iovec,

						inline_vecs, &iter);

		ret = io_setup_async_rw(req, io_size, iovec, inline_vecs,

					&iter);

		if (ret)

			goto out_free;

		/* it's copied and will be cleaned with ->io */

		iovec = NULL;

		return -EAGAIN;

	}

	}

out_free:

	if (iovec)

		kfree(iovec);

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