linux-nvme.lists.infradead.org archive mirror
 help / color / mirror / Atom feed
From: Sagi Grimberg <sagi@grimberg.me>
To: "Meneghini, John" <John.Meneghini@netapp.com>,
	Keith Busch <kbusch@kernel.org>,
	"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
	"hch@lst.de" <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Subject: Re: [PATCH] nvme: Translate more status codes to blk_status_t
Date: Fri, 13 Dec 2019 13:02:47 -0800	[thread overview]
Message-ID: <18f741dd-2445-141e-ea2b-4185476da8d2@grimberg.me> (raw)
In-Reply-To: <C041F01A-6577-4DC4-A992-6F040EC6C0C9@netapp.com>


>      Let me test this out and I’ll see what happens.
>      
> Keith, I've tested this out, using CRD with both NVME_SC_CMD_INTERRUPTED and NVME_SC_NS_NOT_READY.
> 
> It works well enough, but I think the problem goes a little deeper than this.
> 
>> These are not generic IO errors and should use a non-path
>>   specific error so that it can use the non-failover retry path.
> 
> Yes, agreed.  But we have this problem with every/any other NVMe status that gets returned as well.
> It doesn't make sense to just keep overloading the half a dozen errors you have in blk_path_error();
> 
> I think the real problem is here:
> 
>   276         if (unlikely(status != BLK_STS_OK && nvme_req_needs_retry(req))) {
>   277                 if ((req->cmd_flags & REQ_NVME_MPATH) &&
>   278                     blk_path_error(status)) {
>   279                         nvme_failover_req(req);
>   280                         return;
>   281                 }
> "nvme/drivers/nvme/host/core.c" line 281 of 4267 --6%-- col 3-17
> 
> If we are really not allowed to change the blk_path_error() routine because it's a part of
> the block layer, then why do we have it stuck in the middle of our multipathing policy
> logic?
> 
> Maybe we should create an nvme_path_error() function to replace the blk_path_error()
> function here.
> 
> The other problem is: setting REQ_NVME_MPATH completely changes the error
> error handling logic.  If my controller has a single path it happily returns all kinds
> of NVMe errors not handled by the nvme_error_status() white list.  Those
> errors all fall through your retry logic and end up returning  BLK_STS_IOERR.
> 
> However, as soon as we add another path to that same controller, and turn on
> REQ_NVME_MPATH, all of a sudden the controller gets a reset for returning
> the very same errors that it retuned before.

I agree we should lose this controller reset and only do this for
specific error cases where its needed (not thinking of any from the
top of my head).

> And that happens before even a single retry is attempted - unless it's an NVMe pathing error.
> 
> 105         default:
> 106                 /*
> 107                  * Reset the controller for any non-ANA error as we don't know
> 108                  * what caused the error.
> 109                  */
> 110                 nvme_reset_ctrl(ns->ctrl);
> 111                 break;
> 112         }
> "nvme/drivers/nvme/host/multipath.c" line 112 of 739 --15%-- col 1-8
> 
> This makes no sense.

So lets remove this reset. Have the transport take care of this, or do
it only when it is clearly needed.

_______________________________________________
linux-nvme mailing list
linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme

  reply	other threads:[~2019-12-13 22:27 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-05 19:57 Keith Busch
2019-12-12  9:20 ` Christoph Hellwig
2019-12-12 19:41 ` Meneghini, John
2019-12-13  7:32   ` Meneghini, John
2019-12-13 21:02     ` Sagi Grimberg [this message]
2019-12-16  8:02       ` Hannes Reinecke
2019-12-16 15:30         ` Keith Busch

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=18f741dd-2445-141e-ea2b-4185476da8d2@grimberg.me \
    --to=sagi@grimberg.me \
    --cc=John.Meneghini@netapp.com \
    --cc=hare@suse.de \
    --cc=hch@lst.de \
    --cc=kbusch@kernel.org \
    --cc=linux-nvme@lists.infradead.org \
    --subject='Re: [PATCH] nvme: Translate more status codes to blk_status_t' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).