[PATCH 6.8 107/172] io_uring: disable io-wq execution of multishot NOWAIT requests

Greg Kroah-Hartman
2024-04-15T14:28:44Z

From: Jens Axboe <axboe@kernel.dk>

Commit bee1d5becdf5bf23d4ca0cd9c6b60bdf3c61d72b upstream.

Do the same check for direct io-wq execution for multishot requests that
commit 2a975d426c82 did for the inline execution, and disable multishot
mode (and revert to single shot) if the file type doesn't support NOWAIT,
and isn't opened in O_NONBLOCK mode. For multishot to work properly, it's
a requirement that nonblocking read attempts can be done.

Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
io_uring/io_uring.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -1964,10 +1964,15 @@ fail:
err = -EBADFD;
if (!file_can_poll(req->file))
goto fail;
- err = -ECANCELED;
- if (io_arm_poll_handler(req, issue_flags) != IO_APOLL_OK)
- goto fail;
- return;
+ if (req->file->f_flags & O_NONBLOCK ||
+ req->file->f_mode & FMODE_NOWAIT) {
+ err = -ECANCELED;
+ if (io_arm_poll_handler(req, issue_flags) != IO_APOLL_OK)
+ goto fail;
+ return;
+ } else {
+ req->flags &= ~REQ_F_APOLL_MULTISHOT;
+ }
}

if (req->flags & REQ_F_FORCE_ASYNC) {