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X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Apr 2023 17:28:55.9131 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: e474d960-d985-4235-b9db-08db428de283 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BN8NAM11FT028.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB5814 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org When IO_URING_F_NONBLOCK is set on io_kiocb req->flag in io_write() or io_read() IOCB_NOWAIT is set for kiocb when passed it to the respective rw_iter callback. This sets REQ_NOWAIT for underlaying I/O. The result is low level driver always sees block layer request as REQ_NOWAIT even if user has submitted request with nowait = 0 e.g. fio nowait=0. That is not consistent behaviour with other fio ioengine such as libaio as it will issue non REQ_NOWAIT request with REQ_NOWAIT:- libaio nowait = 0:- null_blk: fio:null_handle_rq 1288 *NOWAIT=FALSE* REQ_OP_WRITE libaio nowait = 1:- null_blk: fio:null_handle_rq 1288 *NOWAIT=TRUE* REQ_OP_WRITE * Without this patch with fio ioengine io_uring :- --------------------------------------------------- iouring nowait = 0:- null_blk: fio:null_handle_rq 1288 *NOWAIT=TRUE* REQ_OP_WRITE iouring nowait = 1:- null_blk: fio:null_handle_rq 1288 *NOWAIT=TRUE* REQ_OP_WRITE * With this patch with fio ioengine io_uring :- --------------------------------------------------- iouring nowait = 0:- null_blk: fio:null_handle_rq 1307 *REQ_NOWAIT=FALSE* WRITE iouring nowait = 1: null_blk: fio:null_handle_rq 1307 *REQ_NOWAIT=TRUE* WRITE Instead of only relying on IO_URING_F_NONBLOCK blindly in io_read() and io_write(), also make sure io_kiocb->io_rw->flags is set to RWF_NOWAIT before we mark kiocb->ki_flags = IOCB_NOWAIT. Signed-off-by: Chaitanya Kulkarni --- io_uring/rw.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/io_uring/rw.c b/io_uring/rw.c index 3f118ed46e4f..4b3a2c1df5f2 100644 --- a/io_uring/rw.c +++ b/io_uring/rw.c @@ -745,7 +745,7 @@ int io_read(struct io_kiocb *req, unsigned int issue_flags) } req->cqe.res = iov_iter_count(&s->iter); - if (force_nonblock) { + if (force_nonblock && (rw->flags & RWF_NOWAIT)) { /* If the file doesn't support async, just async punt */ if (unlikely(!io_file_supports_nowait(req))) { ret = io_setup_async_rw(req, iovec, s, true); @@ -877,7 +877,7 @@ int io_write(struct io_kiocb *req, unsigned int issue_flags) } req->cqe.res = iov_iter_count(&s->iter); - if (force_nonblock) { + if (force_nonblock && (rw->flags & RWF_NOWAIT)) { /* If the file doesn't support async, just async punt */ if (unlikely(!io_file_supports_nowait(req))) goto copy_iov;