From: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
To: Hannes Reinecke <hare@suse.de>
Cc: Christoph Hellwig <hch@lst.de>,
linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
Jens Axboe <axboe@fb.com>
Subject: Re: [PATCH 4/4] block: expose devt for GENHD_FL_HIDDEN disks
Date: Fri, 14 Dec 2018 06:56:07 -0200 [thread overview]
Message-ID: <20181214085606.GD5321@calabresa> (raw)
In-Reply-To: <35acb1b3-77f5-29cf-b92d-5171f4ad6450@suse.de>
On Fri, Dec 14, 2018 at 08:47:20AM +0100, Hannes Reinecke wrote:
> On 12/13/18 4:25 PM, Thadeu Lima de Souza Cascardo wrote:
> > On Thu, Dec 13, 2018 at 03:32:18PM +0100, Christoph Hellwig wrote:
> > > On Thu, Dec 13, 2018 at 10:18:40AM +0100, Hannes Reinecke wrote:
> > > > Welll ... this is not just 'lsblk', but more importantly this will force
> > > > udev to create _block_ device nodes for the hidden devices, essentially
> > > > 'unhide' them.
> > > >
> > > > Is this what we want?
> > > > Christoph?
> > > > I thought the entire _point_ of having hidden devices is that the are ...
> > > > well ... hidden ...
> > >
> > > Yes, that is why I really don't like the last two patches.
> > >
> > > And I've checked back - lsblk actually works just fine at the moment.
> > > But it turns out once we create the slave links it stops working,
> > > which is a really good argument against the first two patches, which
> > > would otherwise seem nice..
> >
> > Which is why I have sent the "paths/" patchset in the first place. Because I
> > did some homework and read the previous discussion about this, and how lsblk
> > failure to behave with slave links led to the revert of the slaves/holders
> > patch by Dr. Hannes.
> >
> But you haven't answered my question:
>
> Why can't we patch 'lsblk' to provide the required information even with the
> current sysfs layout?
>
I think we could, but with my Ubuntu hat on, after the kernel fix for
initramfs-tools, that is, slaves/holders links, the user will get an updated
kernel that breaks the current lsblk on Bionic (Ubuntu 18.04). That will
require that we backport the lsblk fix, which is not only more work, but there
may be users who only update from -security, which is where kernel updates end
regularly, but not this lsblk fix.
And that kernel update is a regression against that old lsblk version.
Cascardo.
> Cheers,
>
> Hannes
> --
> Dr. Hannes Reinecke Teamlead Storage & Networking
> hare@suse.de +49 911 74053 688
> SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
> GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
> HRB 21284 (AG Nürnberg)
next prev parent reply other threads:[~2018-12-14 8:56 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-06 16:48 [PATCH 0/4] nvme multipath: expose slaves/holders Thadeu Lima de Souza Cascardo
2018-12-06 16:48 ` [PATCH 1/4] block: move holder tracking from struct block_device to hd_struct Thadeu Lima de Souza Cascardo
2018-12-13 9:14 ` Hannes Reinecke
2018-12-06 16:48 ` [PATCH 2/4] nvme: create slaves/holder entries for multipath devices Thadeu Lima de Souza Cascardo
2018-12-13 9:15 ` Hannes Reinecke
2018-12-06 16:48 ` [PATCH 3/4] nvme: Should not warn when a disk path is opened Thadeu Lima de Souza Cascardo
2018-12-13 9:16 ` Hannes Reinecke
2018-12-06 16:48 ` [PATCH 4/4] block: expose devt for GENHD_FL_HIDDEN disks Thadeu Lima de Souza Cascardo
2018-12-06 20:22 ` Christoph Hellwig
2018-12-12 8:32 ` Christoph Hellwig
2018-12-12 12:39 ` Thadeu Lima de Souza Cascardo
2018-12-13 9:18 ` Hannes Reinecke
2018-12-13 11:41 ` Thadeu Lima de Souza Cascardo
2018-12-13 12:19 ` Hannes Reinecke
2018-12-13 16:08 ` Thadeu Lima de Souza Cascardo
2018-12-13 14:32 ` Christoph Hellwig
2018-12-13 15:25 ` Thadeu Lima de Souza Cascardo
2018-12-13 20:20 ` Christoph Hellwig
2018-12-13 21:00 ` Thadeu Lima de Souza Cascardo
2018-12-14 7:47 ` Hannes Reinecke
2018-12-14 8:56 ` Thadeu Lima de Souza Cascardo [this message]
2018-12-14 9:06 ` Thadeu Lima de Souza Cascardo
2018-12-14 9:54 ` Hannes Reinecke
2018-12-14 10:18 ` Hannes Reinecke
2018-12-14 11:09 ` Thadeu Lima de Souza Cascardo
2018-12-14 9:44 ` Hannes Reinecke
2018-12-13 9:33 ` [PATCH 0/4] nvme multipath: expose slaves/holders Johannes Thumshirn
2018-12-13 11:35 ` Thadeu Lima de Souza Cascardo
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