From nobody Mon May 13 02:02:40 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1627550001034802.5836553781478; Thu, 29 Jul 2021 02:13:21 -0700 (PDT) Received: from localhost ([::1]:37792 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m926Q-0008Ku-W8 for importer@patchew.org; Thu, 29 Jul 2021 05:13:19 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40628) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m925I-0007K1-Tg; Thu, 29 Jul 2021 05:12:08 -0400 Received: from proxmox-new.maurer-it.com ([94.136.29.106]:46290) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m925G-0006yT-N5; Thu, 29 Jul 2021 05:12:08 -0400 Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id E24EF42C48; Thu, 29 Jul 2021 11:12:01 +0200 (CEST) From: Fabian Ebner To: qemu-devel@nongnu.org Subject: [PATCH v2] block/io_uring: resubmit when result is -EAGAIN Date: Thu, 29 Jul 2021 11:10:29 +0200 Message-Id: <20210729091029.65369-1-f.ebner@proxmox.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=94.136.29.106; envelope-from=f.ebner@proxmox.com; helo=proxmox-new.maurer-it.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , "open list:Linux io_uring" , Stefan Hajnoczi , Julia Suvorova , Max Reitz , Stefan Hajnoczi , Fabian Ebner , Aarushi Mehta , Stefano Garzarella Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZM-MESSAGEID: 1627550003908100001 Content-Type: text/plain; charset="utf-8" Linux SCSI can throw spurious -EAGAIN in some corner cases in its completion path, which will end up being the result in the completed io_uring request. Resubmitting such requests should allow block jobs to complete, even if such spurious errors are encountered. Co-authored-by: Stefan Hajnoczi Reviewed-by: Stefano Garzarella Signed-off-by: Fabian Ebner --- Changes from v1: * Focus on what's relevant for the patch itself in the commit message. * Add Stefan's comment. * Add Stefano's R-b tag (I hope that's fine, since there was no change code-wise). block/io_uring.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/block/io_uring.c b/block/io_uring.c index 00a3ee9fb8..dfa475cc87 100644 --- a/block/io_uring.c +++ b/block/io_uring.c @@ -165,7 +165,21 @@ static void luring_process_completions(LuringState *s) total_bytes =3D ret + luringcb->total_read; =20 if (ret < 0) { - if (ret =3D=3D -EINTR) { + /* + * Only writev/readv/fsync requests on regular files or host b= lock + * devices are submitted. Therefore -EAGAIN is not expected bu= t it's + * known to happen sometimes with Linux SCSI. Submit again and= hope + * the request completes successfully. + * + * For more information, see: + * https://lore.kernel.org/io-uring/20210727165811.284510-3-ax= boe@kernel.dk/T/#u + * + * If the code is changed to submit other types of requests in= the + * future, then this workaround may need to be extended to dea= l with + * genuine -EAGAIN results that should not be resubmitted + * immediately. + */ + if (ret =3D=3D -EINTR || ret =3D=3D -EAGAIN) { luring_resubmit(s, luringcb); continue; } --=20 2.30.2