From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 294C214D451 for ; Tue, 7 May 2024 09:12:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715073140; cv=none; b=ooJ4reZJkW1/kMb0Blt3wnP5Aq/mA8f+2beKSnnDwqZBj1aGuc1aRdiTJv/A/5/lKDm9yw7qW2lKQGtvrDa2nXJhycl+ZcbvDxB8FESmJ+0ILM+HFBprsIHnppnP5JqetZkNHqwg8drVlzvnVKFXNKci34AHQe2SO1+AxsLuoMg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715073140; c=relaxed/simple; bh=VJYq9hH6rq1H8WWmpEWC39L8qDwxA3D67QJ9JSQkURs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=tAygclpiu9U4nk7WpjRSR1iMX5J0Wo20x0SL/5kqbe10RKnmGaPzb8HzsqX08ZmTOVFE/h0umYwSKsOh+WhibEFf6j/S+AClzfvXy6clWyho3+iaD3AMW8w2z8mHOydtWLzweNhTOsHGAlA9jf3qILRTj0prIMiLvktB8xGBszs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mL1iNdOa; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="mL1iNdOa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75938C2BBFC; Tue, 7 May 2024 09:12:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1715073139; bh=VJYq9hH6rq1H8WWmpEWC39L8qDwxA3D67QJ9JSQkURs=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=mL1iNdOa7du3foqjfyM/uapbnM1NnIvGhSLtspOIC4lDwmxrDpjmlNzJNJYUzu5YE kcWhBL42vHf56a9e8ZiZW5VIWFFkxJVGvlWDFDyoIipdy5HS8YO8bqNrPsRJAv725V XY7dFvtFOiIa2m/6+5J1is/5aEEBDCPI3/sJMLvH10FO9dVL5vhAhbLJG0wrO8Utga nxvsIG8AzWTtCZcA/IcKjD1XuOFNhFzG049OLGIRzrQfhGRE5G9SbNiuCyh2EU7YeD 4hdS1jACfxL5/GLG3JrwcJwupTJ0gvZEW1whgTX0R0eDokKrVMRJP3VjfhL5nwgN6k B41DERXj7ch5A== Message-ID: Date: Tue, 7 May 2024 18:12:17 +0900 Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] I/O errors for ALUA state transitions To: Martin Wilck , "Martin K. Petersen" , Christoph Hellwig , Hannes Reinecke , James Bottomley , Ewan Milne Cc: Bart Van Assche , linux-scsi@vger.kernel.org, Martin Wilck , Rajashekhar M A References: <20240503195606.13120-1-mwilck@suse.com> From: Damien Le Moal Content-Language: en-US Organization: Western Digital Research In-Reply-To: <20240503195606.13120-1-mwilck@suse.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/4/24 04:56, Martin Wilck wrote: > When a host is configured with a few LUNs and IO is running, > injecting FC faults repeatedly leads to path recovery problems. > The LUNs have 4 paths each and 3 of them come back active after > say an FC fault which makes two of the paths go down, instead of > all 4. This happens after several iterations of continuous FC faults. > > Reason here is that we're returning an I/O error whenever we're > encountering sense code 06/04/0a (LOGICAL UNIT NOT ACCESSIBLE, > ASYMMETRIC ACCESS STATE TRANSITION) instead of retrying. > > mwilck: Resending a modified version of this patch, which was originally > authored by Rajashekhar M A from Netapp, and submitted in 2021. > Moved the changes to alua_check_sense() as suggested by Mike Christie [1]. > Evan Milne had raised the question whether pg->state should be set to > transitioning in the UA case [2]. I believe that doing this is > correct. SCSI_ACCESS_STATE_TRANSITIONING by itself doesn't cause I/O > errors. Our handler schedules an RTPG, which will only result in an I/O > error condition if the transitioning timeout expires. > > [1] https://lore.kernel.org/all/0bc96e82-fdda-4187-148d-5b34f81d4942@oracle.com/ > [2] https://lore.kernel.org/all/CAGtn9r=kicnTDE2o7Gt5Y=yoidHYD7tG8XdMHEBJTBraVEoOCw@mail.gmail.com/ > > Signed-off-by: Hannes Reinecke > Signed-off-by: Martin Wilck > Co-authored-by: Rajashekhar M A > --- > drivers/scsi/device_handler/scsi_dh_alua.c | 34 +++++++++++++--------- > 1 file changed, 20 insertions(+), 14 deletions(-) > > diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c > index a226dc1b65d7..682d5bb53d14 100644 > --- a/drivers/scsi/device_handler/scsi_dh_alua.c > +++ b/drivers/scsi/device_handler/scsi_dh_alua.c > @@ -414,28 +414,34 @@ static char print_alua_state(unsigned char state) > } > } > > -static enum scsi_disposition alua_check_sense(struct scsi_device *sdev, > - struct scsi_sense_hdr *sense_hdr) > +static enum scsi_disposition alua_handle_state_transition(struct scsi_device *sdev) > { > struct alua_dh_data *h = sdev->handler_data; > struct alua_port_group *pg; > > + /* > + * LUN Not Accessible - ALUA state transition > + */ > + rcu_read_lock(); > + pg = rcu_dereference(h->pg); > + if (pg) > + pg->state = SCSI_ACCESS_STATE_TRANSITIONING; > + rcu_read_unlock(); > + alua_check(sdev, false); > + return NEEDS_RETRY; > +} > + > +static enum scsi_disposition alua_check_sense(struct scsi_device *sdev, > + struct scsi_sense_hdr *sense_hdr) > +{ > switch (sense_hdr->sense_key) { > case NOT_READY: > - if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) { > - /* > - * LUN Not Accessible - ALUA state transition > - */ > - rcu_read_lock(); > - pg = rcu_dereference(h->pg); > - if (pg) > - pg->state = SCSI_ACCESS_STATE_TRANSITIONING; > - rcu_read_unlock(); > - alua_check(sdev, false); > - return NEEDS_RETRY; > - } > + if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) Please keep the comment that spells out what this asc/ascq is. > + return alua_handle_state_transition(sdev); > break; > case UNIT_ATTENTION: > + if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) > + return alua_handle_state_transition(sdev); > if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) { > /* > * Power On, Reset, or Bus Device Reset. -- Damien Le Moal Western Digital Research