Disallow offload IO mode for engines marked with FIO_NO_OFFLOAD

Previous commits did this for all async engines, this can potentially
break existing job files. There are only certain cases where it fails,
for now at least mark io_uring as one of those.

Reported-by: Jeff Furlong <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

Author: axboe

engines/io_uring.c

@@ -806,7 +806,7 @@ static int fio_ioring_close_file(struct thread_data *td, struct fio_file *f)
 static struct ioengine_ops ioengine = {
 	.name			= "io_uring",
 	.version		= FIO_IOOPS_VERSION,
-	.flags			= FIO_ASYNCIO_SYNC_TRIM,
+	.flags			= FIO_ASYNCIO_SYNC_TRIM | FIO_NO_OFFLOAD,
 	.init			= fio_ioring_init,
 	.post_init		= fio_ioring_post_init,
 	.io_u_init		= fio_ioring_io_u_init,

ioengines.c

@@ -45,7 +45,7 @@ static bool check_engine_ops(struct thread_data *td, struct ioengine_ops *ops)
 	 * async engines aren't reliable with offload
 	 */
 	if ((td->o.io_submit_mode == IO_MODE_OFFLOAD) &&
-	    !(ops->flags & FIO_FAKEIO)) {
+	    (ops->flags & FIO_NO_OFFLOAD)) {
 		log_err("%s: can't be used with offloaded submit. Use a sync "
 			"engine\n", ops->name);
 		return true;

ioengines.h

@@ -77,7 +77,8 @@ enum fio_ioengine_flags {
 	FIO_NOSTATS	= 1 << 12,	/* don't do IO stats */
 	FIO_NOFILEHASH	= 1 << 13,	/* doesn't hash the files for lookup later. */
 	FIO_ASYNCIO_SYNC_TRIM
-			= 1 << 14	/* io engine has async ->queue except for trim */
+			= 1 << 14,	/* io engine has async ->queue except for trim */
+	FIO_NO_OFFLOAD	= 1 << 15,	/* no async offload */
 };
 
 /*