From: Mike Snitzer <snitzer@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: dm-devel@redhat.com, linux-block@vger.kernel.org,
linux-scsi@vger.kernel.org
Subject: Re: [for-4.14 RFC PATCH 0/2] dm rq: eliminate historic blk-mq and .request_fn queue stacking restrictions
Date: Fri, 14 Jul 2017 10:02:06 -0400 [thread overview]
Message-ID: <20170714140206.GA18245@redhat.com> (raw)
In-Reply-To: <20170714071257.GB17046@lst.de>
On Fri, Jul 14 2017 at 3:12am -0400,
Christoph Hellwig <hch@lst.de> wrote:
> Btw, we might want to expedite this to 4.13, a 4.13 now defaults
> to blk-mq for scsi, and this patch would make sure that dm keeps
> on just working with that switch.
Don't think we need to rush anything in response to that change in
SCSI's default. old .request_fn DM multipath works happily ontop of
blk-mq devices (so long as all paths are blk-mq).
Similarly, blk-mq DM multipath works ontop of all blk-mq devices.
Lastly, old .request_fn DM multipath ontop of old .request_fn paths
works fine.
It is just blk-mq DM multipath ontop of old .request_fn paths that is
disallowed in current upstream code.
But again, I really don't see why we should even want/need to support
that mode... hence my question raised in this RFC.
next prev parent reply other threads:[~2017-07-14 14:02 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-13 21:12 [for-4.14 RFC PATCH 0/2] dm rq: eliminate historic blk-mq and .request_fn queue stacking restrictions Mike Snitzer
2017-07-13 21:12 ` [for-4.14 RFC PATCH 1/2] dm rq: avoid deadlock if dm-mq is stacked on old .request_fn device(s) Mike Snitzer
2017-07-14 7:22 ` Christoph Hellwig
2017-07-14 14:19 ` Mike Snitzer
2017-07-14 17:17 ` Ewan D. Milne
2017-07-14 21:15 ` Mike Snitzer
2017-07-13 21:12 ` [for-4.14 RFC PATCH 2/2] dm rq: eliminate historic blk-mq and .request_fn queue stacking restrictions Mike Snitzer
2017-07-14 7:12 ` [for-4.14 RFC PATCH 0/2] " Christoph Hellwig
2017-07-14 14:02 ` Mike Snitzer [this message]
2017-07-15 8:44 ` Christoph Hellwig
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=20170714140206.GA18245@redhat.com \
--to=snitzer@redhat.com \
--cc=dm-devel@redhat.com \
--cc=hch@lst.de \
--cc=linux-block@vger.kernel.org \
--cc=linux-scsi@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).