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: 11+ 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 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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.