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 0F091C433F5 for ; Tue, 25 Jan 2022 14:40:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1388564AbiAYOkG (ORCPT ); Tue, 25 Jan 2022 09:40:06 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:32802 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232614AbiAYOhR (ORCPT ); Tue, 25 Jan 2022 09:37:17 -0500 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 ams.source.kernel.org (Postfix) with ESMTPS id 25D99B8180E; Tue, 25 Jan 2022 14:37:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4B83CC340E0; Tue, 25 Jan 2022 14:37:04 +0000 (UTC) Date: Tue, 25 Jan 2022 09:37:02 -0500 From: Steven Rostedt To: Yang Shi Cc: Cong Wang , linux-block@vger.kernel.org, Linux Kernel Mailing List , Jens Axboe Subject: Re: [Patch v3] block: introduce block_rq_error tracepoint Message-ID: <20220125093702.3ffdb721@gandalf.local.home> In-Reply-To: References: <20200203053650.8923-1-xiyou.wangcong@gmail.com> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Mon, 24 Jan 2022 12:54:01 -0800 Yang Shi wrote: > Hi folks, > > I think the problems fixed by this patch still exist and we do need > this patch to make disk error handling in rasdaemon easier. I saw > Steven already gave his reviewed-by, I'm wondering why this patch was > not merged to upstream? I didn't see any unsolved comments. Maybe I did that prematurely, as I think I found a mistake in the tracing below. > > If it looks fine, would Jens (I guess it should go with block tree) > please merge this patch upstream? The latest kernel moved > blk_update_request() to blk-mq.c, if it is ok to move forward, I could > prepare a new version. > > Thanks, > Yang > > On Sun, Feb 2, 2020 at 11:15 PM Cong Wang wrote: > > > > Currently, rasdaemon uses the existing tracepoint block_rq_complete > > and filters out non-error cases in order to capture block disk errors. > > > > But there are a few problems with this approach: > > > > 1. Even kernel trace filter could do the filtering work, there is > > still some overhead after we enable this tracepoint. > > > > 2. The filter is merely based on errno, which does not align with kernel > > logic to check the errors for print_req_error(). > > > > 3. block_rq_complete only provides dev major and minor to identify > > the block device, it is not convenient to use in user-space. > > > > So introduce a new tracepoint block_rq_error just for the error case > > and provides the device name for convenience too. With this patch, > > rasdaemon could switch to block_rq_error. > > > > Cc: Jens Axboe > > Cc: Steven Rostedt > > Signed-off-by: Cong Wang > > --- > > block/blk-core.c | 4 +++- > > include/trace/events/block.h | 41 ++++++++++++++++++++++++++++++++++++ > > 2 files changed, 44 insertions(+), 1 deletion(-) > > > > diff --git a/block/blk-core.c b/block/blk-core.c > > index 089e890ab208..0c7ad70d06be 100644 > > --- a/block/blk-core.c > > +++ b/block/blk-core.c > > @@ -1450,8 +1450,10 @@ bool blk_update_request(struct request *req, blk_status_t error, > > #endif > > > > if (unlikely(error && !blk_rq_is_passthrough(req) && > > - !(req->rq_flags & RQF_QUIET))) > > + !(req->rq_flags & RQF_QUIET))) { > > + trace_block_rq_error(req, blk_status_to_errno(error), nr_bytes); > > print_req_error(req, error, __func__); > > + } > > > > blk_account_io_completion(req, nr_bytes); > > > > diff --git a/include/trace/events/block.h b/include/trace/events/block.h > > index 81b43f5bdf23..575054e7cfa0 100644 > > --- a/include/trace/events/block.h > > +++ b/include/trace/events/block.h > > @@ -145,6 +145,47 @@ TRACE_EVENT(block_rq_complete, > > __entry->nr_sector, __entry->error) > > ); > > > > +/** > > + * block_rq_error - block IO operation error reported by device driver > > + * @rq: block operations request > > + * @error: status code > > + * @nr_bytes: number of completed bytes > > + * > > + * The block_rq_error tracepoint event indicates that some portion > > + * of operation request has failed as reported by the device driver. > > + */ > > +TRACE_EVENT(block_rq_error, > > + > > + TP_PROTO(struct request *rq, int error, unsigned int nr_bytes), > > + > > + TP_ARGS(rq, error, nr_bytes), > > + > > + TP_STRUCT__entry( > > + __field( dev_t, dev ) > > + __string( name, rq->rq_disk ? rq->rq_disk->disk_name : "?") > > + __field( sector_t, sector ) > > + __field( unsigned int, nr_sector ) > > + __field( int, error ) > > + __array( char, rwbs, RWBS_LEN ) Why is the above not "__string" ? > > + ), > > + > > + TP_fast_assign( > > + __entry->dev = rq->rq_disk ? disk_devt(rq->rq_disk) : 0; > > + __assign_str(name, rq->rq_disk ? rq->rq_disk->disk_name : "?"); __assign_str() will not work on an __array() type. It only works here because you added it at the end, but it's just shear luck that it didn't crash. -- Steve > > + __entry->sector = blk_rq_pos(rq); > > + __entry->nr_sector = nr_bytes >> 9; > > + __entry->error = error; > > + > > + blk_fill_rwbs(__entry->rwbs, rq->cmd_flags, nr_bytes); > > + ), > > + > > + TP_printk("%d,%d %s %s %llu + %u [%d]", > > + MAJOR(__entry->dev), MINOR(__entry->dev), > > + __get_str(name), __entry->rwbs, > > + (unsigned long long)__entry->sector, > > + __entry->nr_sector, __entry->error) > > +); > > + > > DECLARE_EVENT_CLASS(block_rq, > > > > TP_PROTO(struct request_queue *q, struct request *rq), > > -- > > 2.21.1 > >