From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754320AbcHUPej (ORCPT ); Sun, 21 Aug 2016 11:34:39 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:55749 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754251AbcHUPeg (ORCPT ); Sun, 21 Aug 2016 11:34:36 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: James Bottomley , "James E . J . Bottomley" , "Martin K . Petersen" , Jack Wang , Greg Kroah-Hartman , Willy Tarreau Subject: [PATCH 3.10 155/180] scsi_lib: correctly retry failed zero length REQ_TYPE_FS commands Date: Sun, 21 Aug 2016 17:31:25 +0200 Message-Id: <1471793510-13022-156-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1471793510-13022-1-git-send-email-w@1wt.eu> References: <1471793510-13022-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: James Bottomley commit a621bac3044ed6f7ec5fa0326491b2d4838bfa93 upstream. When SCSI was written, all commands coming from the filesystem (REQ_TYPE_FS commands) had data. This meant that our signal for needing to complete the command was the number of bytes completed being equal to the number of bytes in the request. Unfortunately, with the advent of flush barriers, we can now get zero length REQ_TYPE_FS commands, which confuse this logic because they satisfy the condition every time. This means they never get retried even for retryable conditions, like UNIT ATTENTION because we complete them early assuming they're done. Fix this by special casing the early completion condition to recognise zero length commands with errors and let them drop through to the retry code. Reported-by: Sebastian Parschauer Signed-off-by: James E.J. Bottomley Tested-by: Jack Wang Signed-off-by: Martin K. Petersen [ jwang: backport from upstream 4.7 to fix scsi resize issue ] Signed-off-by: Jack Wang Signed-off-by: Greg Kroah-Hartman Signed-off-by: Willy Tarreau --- drivers/scsi/scsi_lib.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index dc96905..60031e1 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -790,9 +790,12 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) } /* - * If we finished all bytes in the request we are done now. + * special case: failed zero length commands always need to + * drop down into the retry code. Otherwise, if we finished + * all bytes in the request we are done now. */ - if (!blk_end_request(req, error, good_bytes)) + if (!(blk_rq_bytes(req) == 0 && error) && + !blk_end_request(req, error, good_bytes)) goto next_command; /* -- 2.8.0.rc2.1.gbe9624a