io_uring: further simplify do_read error parsing

First, instead of checking iov_iter_count(iter) for 0 to find out that
all needed bytes were read, just compare returned code against io_size.
It's more reliable and arguably cleaner.

Also, place the half-read case into an else branch and delete an extra
label.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 866e0ea..1d1fa1f 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3552,19 +3552,18 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
                /* some cases will consume bytes even on error returns */
                iov_iter_revert(iter, io_size - iov_iter_count(iter));
                ret = 0;
-               goto copy_iov;
-       } else if (ret <= 0) {
+       } else if (ret <= 0 || ret == io_size) {
                /* make sure -ERESTARTSYS -> -EINTR is done */
                goto done;
-       }
+       } else {
+               /* we did blocking attempt. no retry. */
+               if (!force_nonblock || (req->file->f_flags & O_NONBLOCK) ||
+                   !(req->flags & REQ_F_ISREG))
+                       goto done;
 
-       /* read it all, or we did blocking attempt. no retry. */
-       if (!iov_iter_count(iter) || !force_nonblock ||
-           (req->file->f_flags & O_NONBLOCK) || !(req->flags & REQ_F_ISREG))
-               goto done;
+               io_size -= ret;
+       }
 
-       io_size -= ret;
-copy_iov:
        ret2 = io_setup_async_rw(req, iovec, inline_vecs, iter, true);
        if (ret2) {
                ret = ret2;