From: Mike Snitzer <snitzer@redhat.com>
To: kj@orbekk.com
Cc: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>,
Alasdair G Kergon <agk@redhat.com>,
"dm-devel@redhat.com" <dm-devel@redhat.com>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"harshads@google.com" <harshads@google.com>,
Khazhismel Kumykov <khazhy@google.com>
Subject: Re: dm: track io errors per mapped device
Date: Fri, 8 May 2020 17:09:26 -0400 [thread overview]
Message-ID: <20200508210926.GB19773@redhat.com> (raw)
In-Reply-To: <dd7b8b91-776b-4458-a83a-18ab4953d2f4@www.fastmail.com>
On Fri, May 08 2020 at 3:22pm -0400,
kj@orbekk.com <kj@orbekk.com> wrote:
> On Thu, May 7, 2020, at 21:12, Chaitanya Kulkarni wrote:
> > On 05/07/2020 04:06 PM, Kjetil Orbekk wrote:
> > > + if (tio->error)
> > > + atomic_inc(&md->ioerr_cnt);
> >
> > Given that there are so many errors how would user know what
> > kind of error is generated and how many times?
>
> The intended use case is to provide an easy way to check if errors
> have occurred at all, and then the user needs to investigate using
> other means. I replied with more detail to Alasdair's email.
But most operations initiated by the user that fail will be felt by the
upper layer that the user is interfacing with.
Only exception that springs to mind is dm-writecache's writeback that
occurs after writes have already been acknowledged back to the upper
layers -- in that case dm-writecache provides an error flag that is
exposed via writecache_status.
Anyway, just not seeing why you need a upper-layer use-case agnostic
flag to know an error occurred in DM. That layers that interface with
the DM device will have been notified of all errors.
And why just for DM devices? Why not all block devices (in which case
DM would get this feature "for free")?
Mike
next prev parent reply other threads:[~2020-05-08 21:09 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-07 23:05 [PATCH] dm: track io errors per mapped device Kjetil Orbekk
2020-05-08 0:18 ` Alasdair G Kergon
2020-05-08 19:18 ` kj
2020-05-08 1:12 ` Chaitanya Kulkarni
2020-05-08 19:22 ` kj
2020-05-08 21:09 ` Mike Snitzer [this message]
2020-05-09 16:01 ` kj
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=20200508210926.GB19773@redhat.com \
--to=snitzer@redhat.com \
--cc=Chaitanya.Kulkarni@wdc.com \
--cc=agk@redhat.com \
--cc=dm-devel@redhat.com \
--cc=harshads@google.com \
--cc=khazhy@google.com \
--cc=kj@orbekk.com \
--cc=linux-block@vger.kernel.org \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).