io_uring: always go async for unsupported fadvise flags

No point in issuing -> return -EAGAIN -> go async, when it can be done upfront.

Signed-off-by: Dylan Yudaken <dylany@meta.com>
Link: https://lore.kernel.org/r/20230127135227.3646353-4-dylany@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Dylan Yudaken

io_uring/advise.c

@@ -62,6 +62,18 @@ int io_madvise(struct io_kiocb *req, unsigned int issue_flags)
 #endif
 }
 
+static bool io_fadvise_force_async(struct io_fadvise *fa)
+{
+	switch (fa->advice) {
+	case POSIX_FADV_NORMAL:
+	case POSIX_FADV_RANDOM:
+	case POSIX_FADV_SEQUENTIAL:
+		return false;
+	default:
+		return true;
+	}
+}
+
 int io_fadvise_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
 	struct io_fadvise *fa = io_kiocb_to_cmd(req, struct io_fadvise);
@@ -72,6 +84,8 @@ int io_fadvise_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	fa->offset = READ_ONCE(sqe->off);
 	fa->len = READ_ONCE(sqe->len);
 	fa->advice = READ_ONCE(sqe->fadvise_advice);
+	if (io_fadvise_force_async(fa))
+		req->flags |= REQ_F_FORCE_ASYNC;
 	return 0;
 }
 
@@ -80,16 +94,7 @@ int io_fadvise(struct io_kiocb *req, unsigned int issue_flags)
 	struct io_fadvise *fa = io_kiocb_to_cmd(req, struct io_fadvise);
 	int ret;
 
-	if (issue_flags & IO_URING_F_NONBLOCK) {
-		switch (fa->advice) {
-		case POSIX_FADV_NORMAL:
-		case POSIX_FADV_RANDOM:
-		case POSIX_FADV_SEQUENTIAL:
-			break;
-		default:
-			return -EAGAIN;
-		}
-	}
+	WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK && io_fadvise_force_async(fa));
 
 	ret = vfs_fadvise(req->file, fa->offset, fa->len, fa->advice);
 	if (ret < 0)