io_uring/rw: treat -EOPNOTSUPP for IOCB_NOWAIT like -EAGAIN

Some file systems, ocfs2 in this case, will return -EOPNOTSUPP for an IOCB_NOWAIT read/write attempt. While this can be argued to be correct, the usual return value for something that requires blocking issue is -EAGAIN. A refactoring io_uring commit dropped calling kiocb_done() for negative return values, which is otherwise where we already do that transformation. To ensure we catch it in both spots, check it in __io_read() itself as well. Reported-by: Robert Sander <[email protected]> Link: https://fosstodon.org/@[email protected]/113112431889638440 Cc: [email protected] Fixes: a08d195 ("io_uring/rw: split io_read() into a helper") Signed-off-by: Jens Axboe <[email protected]>
noroot · Sep 10, 2024 · c0a9d49 · c0a9d49
1 parent f011c9c
commit c0a9d49
Showing 1 changed file with 8 additions and 0 deletions.
diff --git a/io_uring/rw.c b/io_uring/rw.c
@@ -855,6 +855,14 @@ static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
 
 	ret = io_iter_do_read(rw, &io->iter);
 
+	/*
+	 * Some file systems like to return -EOPNOTSUPP for an IOCB_NOWAIT
+	 * issue, even though they should be returning -EAGAIN. To be safe,
+	 * retry from blocking context for either.
+	 */
+	if (ret == -EOPNOTSUPP && force_nonblock)
+		ret = -EAGAIN;
+
 	if (ret == -EAGAIN || (req->flags & REQ_F_REISSUE)) {
 		req->flags &= ~REQ_F_REISSUE;
 		/* If we can poll, just do that. */