Re: Regression in io_uring, leading to data corruption

[Jens Axboe <axboe@kernel.dk>]

Just to go back to basics, can you try this one? It'll do the exact same
retry that io-wq is doing, just from the same task itself. If this
fails, then something core is wrong. I don't think it will, or we'd see
this on other platforms too of course. If this works, then it validates
that it's some oddity on ppc with punting this operation to a thread off
this main task.

diff --git a/io_uring/rw.c b/io_uring/rw.c
index 64390d4e20c1..1d760570df04 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -968,7 +968,7 @@ int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
 	return IOU_OK;
 }
 
-int io_write(struct io_kiocb *req, unsigned int issue_flags)
+static int __io_write(struct io_kiocb *req, unsigned int issue_flags)
 {
 	struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 	struct io_rw_state __s, *s = &__s;
@@ -1092,6 +1092,19 @@ int io_write(struct io_kiocb *req, unsigned int issue_flags)
 	return ret;
 }
 
+int io_write(struct io_kiocb *req, unsigned int issue_flags)
+{
+	int ret;
+
+	ret = __io_write(req, issue_flags);
+	if (ret != -EAGAIN)
+		return ret;
+
+	ret = __io_write(req, issue_flags & ~IO_URING_F_NONBLOCK);
+	WARN_ON_ONCE(ret == -EAGAIN);
+	return ret;
+}
+
 void io_rw_fail(struct io_kiocb *req)
 {
 	int res;

-- 
Jens Axboe