Merge tag 'io_uring-5.5-2020-01-10' of git://git.kernel.dk/linux-block

Pull io_uring fix from Jens Axboe:
 "Single fix for this series, fixing a regression with the short read
  handling.

  This just removes it, as it cannot safely be done for all cases"

* tag 'io_uring-5.5-2020-01-10' of git://git.kernel.dk/linux-block:
  io_uring: remove punt of short reads to async context

Author: torvalds

fs/io_uring.c

@@ -1863,18 +1863,6 @@ static int io_read(struct io_kiocb *req, struct io_kiocb **nxt,
 		else
 			ret2 = loop_rw_iter(READ, req->file, kiocb, &iter);
 
-		/*
-		 * In case of a short read, punt to async. This can happen
-		 * if we have data partially cached. Alternatively we can
-		 * return the short read, in which case the application will
-		 * need to issue another SQE and wait for it. That SQE will
-		 * need async punt anyway, so it's more efficient to do it
-		 * here.
-		 */
-		if (force_nonblock && !(req->flags & REQ_F_NOWAIT) &&
-		    (req->flags & REQ_F_ISREG) &&
-		    ret2 > 0 && ret2 < io_size)
-			ret2 = -EAGAIN;
 		/* Catch -EAGAIN return for forced non-blocking submission */
 		if (!force_nonblock || ret2 != -EAGAIN) {
 			kiocb_done(kiocb, ret2, nxt, req->in_async);