From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 11C73C433F5 for ; Tue, 10 May 2022 14:23:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344324AbiEJO0T (ORCPT ); Tue, 10 May 2022 10:26:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44246 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244350AbiEJNwy (ORCPT ); Tue, 10 May 2022 09:52:54 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ABCCD7A80C; Tue, 10 May 2022 06:38:19 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 51C44615C8; Tue, 10 May 2022 13:38:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 54BA8C385C6; Tue, 10 May 2022 13:38:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1652189883; bh=1Cs4CGR/T9aWauJL6iNFtwdxt8Jg/kB7NldSroRV47k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PCYo8yz5KE09ntmr3Jef+1UKr/IPN4WNM7RXt7IH0F2xdSmQuUauN8b23fdsPkMJl dAZtaEYCjVcfTXHrYQ2WyhKNjM7w1yxodhMzc3JlS/tEIPHHoUd3oC95iX0xYUcD4M OtPjAaSJYrcmKl2BusKr6mmJrIhBkPV1TmoRHtZE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Stefan Haberland , Jan Hoeppner , Jens Axboe Subject: [PATCH 5.17 042/140] s390/dasd: prevent double format of tracks for ESE devices Date: Tue, 10 May 2022 15:07:12 +0200 Message-Id: <20220510130742.823129293@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220510130741.600270947@linuxfoundation.org> References: <20220510130741.600270947@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Stefan Haberland commit 71f3871657370dbbaf942a1c758f64e49a36c70f upstream. For ESE devices we get an error for write operations on an unformatted track. Afterwards the track will be formatted and the IO operation restarted. When using alias devices a track might be accessed by multiple requests simultaneously and there is a race window that a track gets formatted twice resulting in data loss. Prevent this by remembering the amount of formatted tracks when starting a request and comparing this number before actually formatting a track on the fly. If the number has changed there is a chance that the current track was finally formatted in between. As a result do not format the track and restart the current IO to check. The number of formatted tracks does not match the overall number of formatted tracks on the device and it might wrap around but this is no problem. It is only needed to recognize that a track has been formatted at all in between. Fixes: 5e2b17e712cf ("s390/dasd: Add dynamic formatting support for ESE volumes") Cc: stable@vger.kernel.org # 5.3+ Signed-off-by: Stefan Haberland Reviewed-by: Jan Hoeppner Link: https://lore.kernel.org/r/20220505141733.1989450-3-sth@linux.ibm.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- drivers/s390/block/dasd.c | 7 +++++++ drivers/s390/block/dasd_eckd.c | 19 +++++++++++++++++-- drivers/s390/block/dasd_int.h | 2 ++ 3 files changed, 26 insertions(+), 2 deletions(-) --- a/drivers/s390/block/dasd.c +++ b/drivers/s390/block/dasd.c @@ -1422,6 +1422,13 @@ int dasd_start_IO(struct dasd_ccw_req *c if (!cqr->lpm) cqr->lpm = dasd_path_get_opm(device); } + /* + * remember the amount of formatted tracks to prevent double format on + * ESE devices + */ + if (cqr->block) + cqr->trkcount = atomic_read(&cqr->block->trkcount); + if (cqr->cpmode == 1) { rc = ccw_device_tm_start(device->cdev, cqr->cpaddr, (long) cqr, cqr->lpm); --- a/drivers/s390/block/dasd_eckd.c +++ b/drivers/s390/block/dasd_eckd.c @@ -3083,13 +3083,24 @@ static int dasd_eckd_format_device(struc } static bool test_and_set_format_track(struct dasd_format_entry *to_format, - struct dasd_block *block) + struct dasd_ccw_req *cqr) { + struct dasd_block *block = cqr->block; struct dasd_format_entry *format; unsigned long flags; bool rc = false; spin_lock_irqsave(&block->format_lock, flags); + if (cqr->trkcount != atomic_read(&block->trkcount)) { + /* + * The number of formatted tracks has changed after request + * start and we can not tell if the current track was involved. + * To avoid data corruption treat it as if the current track is + * involved + */ + rc = true; + goto out; + } list_for_each_entry(format, &block->format_list, list) { if (format->track == to_format->track) { rc = true; @@ -3109,6 +3120,7 @@ static void clear_format_track(struct da unsigned long flags; spin_lock_irqsave(&block->format_lock, flags); + atomic_inc(&block->trkcount); list_del_init(&format->list); spin_unlock_irqrestore(&block->format_lock, flags); } @@ -3170,8 +3182,11 @@ dasd_eckd_ese_format(struct dasd_device } format->track = curr_trk; /* test if track is already in formatting by another thread */ - if (test_and_set_format_track(format, block)) + if (test_and_set_format_track(format, cqr)) { + /* this is no real error so do not count down retries */ + cqr->retries++; return ERR_PTR(-EEXIST); + } fdata.start_unit = curr_trk; fdata.stop_unit = curr_trk; --- a/drivers/s390/block/dasd_int.h +++ b/drivers/s390/block/dasd_int.h @@ -188,6 +188,7 @@ struct dasd_ccw_req { void (*callback)(struct dasd_ccw_req *, void *data); void *callback_data; unsigned int proc_bytes; /* bytes for partial completion */ + unsigned int trkcount; /* count formatted tracks */ }; /* @@ -611,6 +612,7 @@ struct dasd_block { struct list_head format_list; spinlock_t format_lock; + atomic_t trkcount; }; struct dasd_attention_data {